# ABA mk1 running hot. Any ideas?



## boraIV (Jan 8, 2001)

I have a caddy with an ABA swapped into it and its running warm even on the freeway just cruising when there should be plenty of airflow. 
Pretty much the entire cooling system is brand new. New hoses, New radiator, Fresh rebuilt motor 

Typical temps from a gentle cruise on surface streets last night (about 10 miles): 
Head 230* 
Lower Hose 155* 
Upper Hose 215* 

Details on the set up: 
ABA decked .040" 
TT 268* cam 
HD valve springs 

New water pump 
New mk1 radiator (non-overflow) 
No oil cooler 
No heater core 
Low temp thermostat 
Low temp fan switch 
2 10" Slim line fans 

I'm running 50/50 G12/distilled water mix. I thought of running 25/75 G12/Water since I'm not worried about freezing temps in Phoenix, but that's still just a band-aid. 

Because of the deleted oil cooler and heater core the only coolant lines are lower rad to water pump and head to radiator. 

The thermostat has 2 small holes drilled through it to help get air out of the system when filling it up, but I did that based on some recommendations from others and don't see that causing an issue due to the small nature of the holes, but maybe it is. I don't know. 

I'm not great at diagnosing this stuff, but I built the whole truck so I'm not afraid of a wrench. 

I just can't figure out why it would be running hot if it's getting adequate airflow (on the freeway for instance).


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## Hurt (May 3, 2011)

No CEL? 

I'd look into trying to get a coolant overflow tank in there somewhere. If you're concerned about looks, hide it somewhere. The small radiator could be the problem.. MK1's have very small radiators from what I've seen. Do you have an electric fan (MK3 style)? If it isn't coming on, that could cause some heating issues. Is it running at, say.. 190* on the temp gauge? That's normal. I'd also say try swapping in a new t-stat. If you drilled holes in it, it could be messing up somehow. You can get a lower temp t-stat, too.


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## ps2375 (Aug 13, 2003)

Is this a fresh built motor, still in break-in? Temps will be elevated if it is, until things wear in.(After about an hour or two of run time you should see temps come down.)

And a stock mkI radiator can handle more HP than you are making with this motor. The overflow can be nice, but I have never had one on my car and have never had any problems, even when towing the race car. 

A bleed hole in the thermostat is good to help prevent an air pocket, or I just partially fill the motor from the upper rad hose to get some fluid on that side of the thermostat.

As long as it is not boiling over, you should be fine. Do your break-in routine and you will see temps come down after rings start to seat and bearings wear in to happy place.


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## boraIV (Jan 8, 2001)

Here is the engine bay and the fan setup. I will consider getting a shroud made but only when I can get temps stable with ample airflow (freeway). 

I am running a mk1 cluster so I don't know if I have a CEL because I haven't plugged a vag com in recently. Fans come on just fine, they are cheap ebays so they may not pull enough cfm but like I said, it should be running cooler at freeway speeds. 

To be honest, I don't know if the bottom end had zero miles when I put it in. I was told so, but not 100%. The head was rebuilt by me, so it is. Either way, I have more than a couple hours on it at this point.


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## ps2375 (Aug 13, 2003)

boraIV said:


> Head 230*
> Lower Hose 155*
> Upper Hose 215*


So, if you have a mkI dash, what are you running the temp gauge with, a mkI style sender? 
And those temps you have don't indicate any problems, the head will be the hottest part, upper hose should be hot and the lower hose shows that the radiator is working.


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## Anony00GT (Mar 6, 2002)

Drilling a tiny hole in the thermostat is fine. It does make it easier to purge the air out of the system, and should have no ill effect. Some T-stats actually come with a predrilled hole and little float, and when I see one of those, I usually remove the float before installation.

I second whoever said to get an overflow bottle.




boraIV said:


> Typical temps from a gentle cruise on surface streets last night (about 10 miles):
> Head 230*
> Lower Hose 155*
> Upper Hose 215*


This doesn't sound too hot. The head is a little on the high side, yes, but not unacceptable by any means.

What is the ambient temp in Phoenix right now? Triple-digits?


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## boraIV (Jan 8, 2001)

Yes it is in the triple digits but really with the motor that I'm running and the weight it's pulling, that shouldn't be much of an issue (at least in my mind). I'm running the temp sensor to the mk1 gauge but I think it reads hot and I don't trust it. I have a VDO gauge w/ sender on the way. Those temps I got were from and infrared thermometer.

I realize those temps aren't _that_ hot... but it was only a 10 mile drive at night coming back from a movie and I was taking it easy because I knew it would get hot if I didn't. On the way to the movie, it was still day light and it was running even warmer and that was all freeway. 

I guess I'll wait for that gauge and start getting some real time information. I also have an oil pressure and oil temp gauge coming. 

What temps should I really start getting concerned at?

Thanks for the help so far!


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## Anony00GT (Mar 6, 2002)

I figured that was an IR thermometer temps you posted.

Well, the upper hose houses the temp sensor and is the hot one. If the sensor in the housing tops 225-230*F, that's where I'd start to be concerned (after you get a known good sensor/gauge of course). At 215* on the upper and 155* on the lower, I'd say that's pretty normal, especially given the high ambient temps. Thermostat and radiator are doing their jobs.

As previously mentioned, you might want to get a bigger radiator, especially given the fact you don't have a heater core to help take heat away in an emergency situation and you do deal with regular temps >100*. I can't tell from the pic what radiator you're running.


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## boraIV (Jan 8, 2001)

Thank you. 

The radiator is a brand new mk1 style rad:
http://www.germanautoparts.com/productdisplay/57125

I'm considering having a friend of mine make a shroud for the fans and also getting an aftermarket oil cooler if the gauges tell me that the oil temps are on the high side.

Once I get the gauges I will post back with more detailed information.


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## Anony00GT (Mar 6, 2002)

boraIV said:


> The radiator is a brand new mk1 style rad:
> http://www.germanautoparts.com/productdisplay/57125


Don't know the dimensions, but based on the picture, that definitely looks smaller than an A3 style radiator. Bigger is better 

Also, put an overflow bottle in it. You'll have to with an A3 radiator anyway.


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## boraIV (Jan 8, 2001)

I think a mk3 style rad is too tall I think.


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## ps2375 (Aug 13, 2003)

Are you running a mkI style temp sender or the mkIII sender? I don't know if the dash will read correctly with the mkIII sender. We've run more motor than that on a mkI radiator and had no issues, That rad will be fine, especially since it is new. An external oil cooler will drop oil temps, of course, and will also take some thermal load off of the water cooling system.


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## Anony00GT (Mar 6, 2002)

ps2375 said:


> Are you running a mkI style temp sender or the mkIII sender? I don't know if the dash will read correctly with the mkIII sender. We've run more motor than that on a mkI radiator and had no issues, That rad will be fine, especially since it is new. An external oil cooler will drop oil temps, of course, and will also take some thermal load off of the water cooling system.


I'm going by the temps he reported via IR thermometer.

Generally, I agree the mk1 rad should be enough in most cases, even this one. All I'm saying is that upgrading to a bigger rad should cause the temps to come down a little. Since he lives in the desert with high ambient temps, that's what I'd do anyway. I have no idea about physical fitment though.


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## boraIV (Jan 8, 2001)

ps2375 said:


> Are you running a mkI style temp sender or the mkIII sender? I don't know if the dash will read correctly with the mkIII sender. We've run more motor than that on a mkI radiator and had no issues, That rad will be fine, especially since it is new. An external oil cooler will drop oil temps, of course, and will also take some thermal load off of the water cooling system.




Yes, which is why I have an aftermarket gauge and sender on the way. Once hooked up, I'll report back.


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## A1steaksauce (Nov 30, 2009)

i agree about the radiator being able to handle the stock aba. heck there are some that are running around with vr swaps running the stock sized mk1 radiator. 

there's nothing wrong with mixing and matching your senders, ie mk3 senders with a mk1 cluster. they will read correctly. heck even vr senders will read and work correctly with mk1 clusters.

you want to upgrade your radiator size? that's easy. mk1 a/c radiator is larger than a standard mk1 radiator. 16v rocco radiator is larger than that. and the most bang for your buck is the 16v passat radiator. all will fit with either minor drilling and/or moving the upper mounting tabs. just keep in mind that when you go to the larger passat unit you'd be wise to run down the corresponding aux fan setup for it. i ran the 16v passat unit on my vr swap and no matter how hard i tried i could never get my motor to run at dead center on the temp gauge. and that was with me bypassing the heater core. she always ran just a touch cooler. 

also curious have you pulled and inspected your thermostat? generally they're stamped with the temp range on them...perhaps you got a higher temp one by mistake?


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## ps2375 (Aug 13, 2003)

A1steaksauce said:


> there's nothing wrong with mixing and matching your senders, ie mk3 senders with a mk1 cluster. they will read correctly. heck even vr senders will read and work correctly with mk1 clusters.


 This I did not know, as I have never done it.


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## boraIV (Jan 8, 2001)

Alright, got all the gauges installed and have some better data to share. I took a little drive (10 minutes or so) during the hottest part of the day. Oil temp seemed pretty steady at 225* and water temp was pretty steady at about 200* until I hit a long light then it climbed to just over 220*. Once I got moving it stayed roughly the same temp even at higher speeds and then when I got home I let it idle in the driveway and was slowly climbing so I shut it down. 

Looks like I might need to get a shroud made so that when I'm sitting still the fans are more efficient. I hope that will help.

The concerning part is that it wasn't a long drive at all and I stayed around my house. If I was in traffic and/or hit multiple lights, I think I'd be overheating. 

Because the truck doesn't have A/C, I'm not going to be driving it much during the heat of the day, but it would be nice to be able to if I wanted.


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## boraIV (Jan 8, 2001)

Thought of something else... When I was cruising around and the temp was sitting at 200*, it shot up to 220* pretty quick and I'm wondering if that is when the thermostat opened up.

If so, that means the thermostat isn't a low temp one.


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## boraIV (Jan 8, 2001)

Anybody? :wave:


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## ps2375 (Aug 13, 2003)

I would start with another thermostat first, cheap and easy initial test, since the whole system is essentially new or very new.


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## Anony00GT (Mar 6, 2002)

Yep. Lower temp thermostat to start definitely. 

Are you sure your fans are turning on?


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## A1steaksauce (Nov 30, 2009)

boraIV, 

my last aba swap i had pretty much the same setup as you except for the fact that i was running my heater core and i had a cooler thermostat and fan switch. even with all those she always ran hot, but never over heated on me. and i wasn't running around in outside temps as hot as you are. 

you see the last page of the aba swap thread how that guy routed the overflow coolant line on the head back into the system? 

i'm wondering if that's your issue right there, plugging that line off. i had my line plugged as well and i was going to go ahead and swap my setup back to a coolant bottle setup...hook it up like mk3 stock-wise to see if that made a difference...but the car found a new home before i got to test my theory. 

it wouldn't be too hard to quickly fab up something for testing purposes...and heck i'd love to know if that sorts out your issue :beer:


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## boraIV (Jan 8, 2001)

Anony00GT said:


> Yep. Lower temp thermostat to start definitely.
> 
> Are you sure your fans are turning on?


 Positive.


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## boraIV (Jan 8, 2001)

A1steaksauce said:


> boraIV,
> 
> my last aba swap i had pretty much the same setup as you except for the fact that i was running my heater core and i had a cooler thermostat and fan switch. even with all those she always ran hot, but never over heated on me. and i wasn't running around in outside temps as hot as you are.
> 
> ...


 
Hmmm, you got me thinking now. Somebody else mentioned that but it was a long time ago. The port on the coolant flange is permanently capped so I'd have to get another one... I'll try the thermostat first and if that doesn't change it, I'll try that next. :thumbup: 

Dammit, i just want to drive it!


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## InSaneV (Oct 24, 2009)

Have you tried this yet? Thinking the same as A1 have mine capped like most do and find the temp runs a tad warmer than when I had my old 1.7 in the car. Going to reroute the head overflow line into the the coolent tube that had the bottle return line to it.


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## boraIV (Jan 8, 2001)

InSaneV said:


> Have you tried this yet? Thinking the same as A1 have mine capped like most do and find the temp runs a tad warmer than when I had my old 1.7 in the car. Going to reroute the head overflow line into the the coolent tube that had the bottle return line to it.


 I haven't I've been out of town and will try it when I get back.:thumbup:


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## Anony00GT (Mar 6, 2002)

boraIV said:


> Hmmm, you got me thinking now. Somebody else mentioned that but it was a long time ago. The port on the coolant flange is permanently capped so I'd have to get another one... I'll try the thermostat first and if that doesn't change it, I'll try that next. :thumbup:
> 
> Dammit, i just want to drive it!


 The coolant line on the head? That one's not in the plastic flange, it's a metal nipple on the head that goes into a hose and back to the bottle. Yes, that line is how air is purged through the system and back through the bottle. 

I mentioned to set up an overflow earlier. Since it's an ABA engine, it's definitely advisable to run an A3 (closed system) setup with the reservoir and all. 

I just tool another look at that pic of your engine bay. The picture isn't great, but I looking again I don't see a pressure cap anywhere. Heck, how do you fill it? That's not a setup I'd want to be using.


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## boraIV (Jan 8, 2001)

Anony00GT said:


> The coolant line on the head? That one's not in the plastic flange, it's a metal nipple on the head that goes into a hose and back to the bottle. Yes, that line is how air is purged through the system and back through the bottle.
> 
> I mentioned to set up an overflow earlier. Since it's an ABA engine, it's definitely advisable to run an A3 (closed system) setup with the reservoir and all.
> 
> I just tool another look at that pic of your engine bay. The picture isn't great, but I looking again I don't see a pressure cap anywhere. Heck, how do you fill it? That's not a setup I'd want to be using.


 I'm not setting up an overflow bottle unless it's ABSOLUTELY necessary. There are other people running this setup with no problems. 

What we were talking about with the coolant flange was routing that metal nipple on the head into the port on the coolant flange. 

The pressure cap is on the radiator, right hand side. It's a black cap.


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## Anony00GT (Mar 6, 2002)

boraIV said:


> I'm not setting up an overflow bottle unless it's ABSOLUTELY necessary. There are other people running this setup with no problems.
> 
> What we were talking about with the coolant flange was routing that metal nipple on the head into the port on the coolant flange.
> 
> The pressure cap is on the radiator, right hand side. It's a black cap.


 OK now I see it. Nevermind. You shouldn't _need_ an overflow with that setup then.


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## A1steaksauce (Nov 30, 2009)

Anony00GT said:


> OK now I see it. Nevermind. You shouldn't _need_ an overflow with that setup then.


 but here's the kicker...there's 3 of us that are currently running this way and all of us are running a tad bit warmer. 

i'm totally in to see if routing that line off the head back into the coolant flange will solve this issue of warmer running :beer: 

boraIV, please do this and report back good sir :thumbup: opcorn:


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## InSaneV (Oct 24, 2009)

I took my jetta to a local meet and cruz Friday night car worked great, and with the cruize I noticed something. If i drive like a good citizen my temps stay pretty much bang on with normal operating temps. High way speeds or spirited driving brings it up to the higher temp range and sits there till I come to a stop and idle or drive reg street speeds again. 

So from this I gather that maybe putting back the rad flaps that kinda funnel the air to go thru the rad more at higher speeds would help, but def going to reroute the head spout to get run back into the coolent pipe return. If it rains tomorrow ill do the hose reroute and report!


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## boraIV (Jan 8, 2001)

InSaneV said:


> I took my jetta to a local meet and cruz Friday night car worked great, and with the cruize I noticed something. If i drive like a good citizen my temps stay pretty much bang on with normal operating temps. High way speeds or spirited driving brings it up to the higher temp range and sits there till I come to a stop and idle or drive reg street speeds again.
> 
> So from this I gather that maybe putting back the rad flaps that kinda funnel the air to go thru the rad more at higher speeds would help, but def going to reroute the head spout to get run back into the coolent pipe return. If it rains tomorrow ill do the hose reroute and report!


Weird I had pretty much the opposite experience today! Granted it was only 90* and not 110* outside but the humidity was pretty nasty @ 65% or so. 


I'm thinking there is air in my system... I drove it for about an hour this morning and was taking it really easy because I needed to get the truck somewhere and didn't want to risk overheating. The temp gauge would fluctuate a bit from 205* - 215* and start to climb to about 220* on the freeway. If I was cruising along and then let off the gas suddenly, the temp would drop instantly. This made me wonder about possible air in the system so I did an experiment. 

On the way back home I decided to get on it pretty good and as soon as I did that, my gauge was pegged straight up at 200* and didn't budge the whole way. This begs the question, how the hell do I get all the air out of the system then? The T-stat has a couple holes drilled in it to help there, I've massaged the lines and filled them up in several different ways… Could the capped overflow nipple on the head be CAUSING air in the system in that it's just not flowing correctly?


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## InSaneV (Oct 24, 2009)

Hum now im stummped, as mine is different than yours. For the most part my drive is like 15m to and then back from work. So i normally dont get to see what a prolonged drive will do. So this week i have been watching it closesly and even put vcds on it to watch the temps. Mine will spike up to the low to mid 200's then drop the longer I drive, down to about half which was the normal operating temp on the older motor. I just did a nice 100k drive to a nearby town and after the first 15m she would settle in at half and move a bit up and down but stayed pretty even. Still havent rerouted yet but im going to try this weekend since my starter just crapped out on me after that drive........sigh so ill be wrenching period.


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## boraIV (Jan 8, 2001)

Yeah I havent bought a new coolant flange yet and I'm not sure how I'm going to connect the hose to the larger heater core outlet...

I wish I still had my overflow style rad, I could just run the line right to the the nipple on it.


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## ps2375 (Aug 13, 2003)

boraIV said:


> I'm thinking there is air in my system... I drove it for about an hour this morning and was taking it really easy because I needed to get the truck somewhere and didn't want to risk overheating. The temp gauge would fluctuate a bit from 205* - 215* and start to climb to about 220* on the freeway. If I was cruising along and then let off the gas suddenly, the temp would drop instantly. This made me wonder about possible air in the system so I did an experiment.
> 
> On the way back home I decided to get on it pretty good and as soon as I did that, my gauge was pegged straight up at 200* and didn't budge the whole way. This begs the question, how the hell do I get all the air out of the system then? The T-stat has a couple holes drilled in it to help there, I've massaged the lines and filled them up in several different ways… Could the capped overflow nipple on the head be CAUSING air in the system in that it's just not flowing correctly?


This sounds more like a ground/sensor issue, as water temp will not fluctuate instantly with the action of the throttle.


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## boraIV (Jan 8, 2001)

I guess but that's why I was thinking an air bubble. If it was a ground issue, then it would peg hot or something.

Also, once I was driving it hard and the gauge was steady at 200* it just sat there like there was never an issue.


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## A1steaksauce (Nov 30, 2009)

boraIV said:


> Yeah I havent bought a new coolant flange yet and I'm not sure how I'm going to connect the hose to the larger heater core outlet...


try hitting up anlxn. he's running his coolant line this way and he posted a pic of his setup in the aba swap thread...but his pic really doesn't show too well what he came up with :beer:


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## boraIV (Jan 8, 2001)

I think he mentioned something about having a custom machined barb made for it. I'll check. Another thought I had, which wouldn't be as clean, is just running a cap that has a nipple on it (if they exist) and running it to that. It would be simple enough at least to test our theory.

edit: They do exist.


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## ps2375 (Aug 13, 2003)

the nipple on that cap is just for directing the relief overflow to a bottle, and that particular one was from a Vanagon.


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## boraIV (Jan 8, 2001)

Well damn.


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## A1steaksauce (Nov 30, 2009)

boraIV said:


> I think he mentioned something about having a custom machined barb made for it. I'll check.


i have faith that you and Lowes could come up with something that would work. you two should get together and build that :laugh:

but honestly i think that you could come up with a homemade step of sorts to at least test the theory. then if it's correct then it wouldn't be anything a decent fab shop couldn't make you a cleaner version for not a lot of money :beer:


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## boraIV (Jan 8, 2001)

ps2375 said:


> the nipple on that cap is just for directing the relief overflow to a bottle, and that particular one was from a Vanagon.


So does this nipple have a valve in it that would prevent flow from the head?


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## ps2375 (Aug 13, 2003)

Flow from the head? That is for the radiator and it the rad overflows it comes out there and goes to where the hose goes. Then when it cools off, it will draw the coolant back in. The only valve is the normal press valve in any radiator cap.


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## boraIV (Jan 8, 2001)

right, but what we're trying to achieve here is normal flow from the head back into the normal stream of coolant. So what if we just attach a hose from the head to the nipple on this rad cap? It should at least provide some flow, no? Unless pressure is higher at the rad cap than at the head, but I don't see how that's possible in a closed system. Pressure should be equal in both if not a bit higher in the head due to the water pump...


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## ps2375 (Aug 13, 2003)

That cap was never meant to have flow thru it. W/O gutting it, there will be no flow thru it. And you would not have any overflow protection.


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## boraIV (Jan 8, 2001)

I don't have any overflow protection now and the flow from the head is a trickle.


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## boraIV (Jan 8, 2001)

Well, I just made a 30 mile drive to a gtg and back (all freeway) and my oil temp never topped 260* and water temp never topped ~215*. That being said, my water temp gauge is fluctuating so much there HAS to be air in the system. Whether thats from not burping it enough or from the capped head outlet is unknown. I'm thinking it's the latter. 

It's about 95* outside. Looks like an oil cooler might be a good idea, eh?


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## ps2375 (Aug 13, 2003)

boraIV said:


> my water temp gauge is fluctuating so much there HAS to be air in the system. Whether thats from not burping it enough or from the capped head outlet is unknown. I'm thinking it's the latter.


Is it jumping around or slowly moving? If it is the former, you have instrument issues.


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## boraIV (Jan 8, 2001)

It jumps around quite a bit. I'll try to get a video next time I drive it. I don't believe it's wiring because it never ever fully pegs or loses a reading. It's just fluctuating between 200*-220*.


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## ps2375 (Aug 13, 2003)

That is totally not right. Water temp won't vary that much that fast.


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## InSaneV (Oct 24, 2009)

I'd say a bad grnd ... temp stays pretty soild once i have been running for longer than 15m ....though i do wonder why it does climb the the mid 200's for a bit then decide to level off to normal operating levels.


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## boraIV (Jan 8, 2001)

I'll triple check the ground, but it's grounded at the same spot my other 2 VDO gauges are and they don't exhibit the same behavior.


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