# 1.6 L Diesel... Oil Pressure Light When Starting



## nateturn (Mar 9, 2009)

Hello All, 

I just have a quick question about how long the oil pressure light should stay on after starting my 89 VW Jetta with 1.6L Diesel (normally aspirated). My Dad and I rebuilt this engine at about 170K miles and it's now at 208 thousand. We did a slightly low budget rebuild... Had the Head reconditioned, used new pistons and rings, but did not replace rods and just replaced the Main and Rod Bearings without having the Crank ground (because the crank didn't show wear when mic'd). The thing sounds terrible and runs great just like it's supposed to and gets 43-47mpg! 

I think the Oil pressure light has been staying on a little longer than it used to after starting. My book just says that it should go off when started, but should it do so immediately? After a cold start, my Oil Pressure light always flashes once, sometimes a second short "half flash" also occurs. Doesn't always flash once when it's warmed up. Anyone have any insight? How long does your oil pressure lights stay on? Does this indicate engine wear? Is this going to shorten my engine life? Are there things to check? Oil Pump? 

Thanks, 
Nate


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## rdezsofi (Sep 21, 2010)

My '86 1.6 diesel NA in a Golf......rebuilt about 35,000 miles ago....oil light goes off in a second or less. Doesn't flash back on at all. The light is controlled by the low pressure sending unit. Found on the transmission side of the cylinder head, a one-wire connection. The colder the weather, the longer for oil pressure to reach it as the oil is thicker. Likewise, a heavier weight oil like 15w40will take longer to reach the unit than a 5w40. The time factor for the light to come on is likely related to the above....however, flashing back on is a possible issue. 

Inexpensive checks first: 

1. Replace the sending unit. Under 10 dollars, frequently around 5 dollars. Make sure the connection is good and clean. (I soldered a new connector to the wire on mine....original one was looking not-so-good.) 

2. Pick up a basic mechanical oil pressure gauge. $12 at Autozone. Temporarily hook it up to where that sending unit is. Have someone start the car and watch it. When the pressure hits it, the needle will swing steadily up. On a cold engine, don't be surprised if it exceeds 100 psi, then drops slowly as the engine warms. I run 15 psi fully warmed up at an idle.....but the only spec VW gives is 28 psi at 2000 rpm when warm. 

3. Pull out the vacuum pump and replace the seal inside the bottom of the gear. It's VW part number #068 145 117 B REPLACE this inexpensive seal, only available from the VW dealer. It affects oil pressure at start up and at idle. 

4. If the oil pressure is on the low side still, you're probably looking at the intermediate shaft bearings. Around 20 dollars, but you'll pull the engine to replace them. Before deciding on this, buy a new oil pump....the high volume one with the 36mm gears....about $100 for a German one. 

I would bet money it's just the cheap sending unit. But if you didn't replace the oil pump with a high volume one when you did the economy rebuild, it's never too late for this upgrade. If you reused the oil pump, take a close look at the screen in the pick-up tube...I'll bet it's partially blocked by carbon and other stuff. Simply drop the pan, pull the vacuum pump, 2 bolts for the oil pump and put it back together. I 'pre-lube' everything once the new pump is in, by using a socket that fits right on the oil pump shaft with an electric drill....be ready for when it picks up oil or it'll twist the drill right out of your hands. Keep running it for a minute or two and it's set to go.


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## nateturn (Mar 9, 2009)

Thanks for the Ideas!

I will check the connection to the sending unit and may replace it if I can get a German one. I have learned to be wary of re-manufactured (Brazilian) parts. It seems logical to me that the Sending unit is working properly though, because it is either signaling low oil pressure or it's not, and it indicates that the Oil pressure returns to normal a few seconds after starting, as it should. It seems likely to me that the oil pressure is staying low for longer than it should. Which could be explained by the Seal in the Vacuum pump, or a plugged pickup screen in the Oil Pump. I will check all of these things and try to report back. 

About the higher volume oil pump... Is this really a good idea? Wouldn't that increase my oil pressure further at all times, when I am only concerned about the pressure just after starting. I would be nervous increasing baseline pressure during the warm up period when pressure is highest. I recently checked my oil pressure and it seemed very high! Like 150psi or more! I can't remember exactly. I've heard accounts of diesel oil filter seals blowing out because of the high pressure, so I don't know that I would want to increase it more. Thanks for the help, I'll check the things suggested but in the mean time does anyone have a link to information about the high volume oil pump for a VW 1.6 liter diesel? 

Thanks,
Nate


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## kinewman944 (Oct 16, 2008)

*sorry to butt in....*

I was just wondering what the color of the oil psi wire is? I have a brown wire and a black with green wire hanging off my wiring harness below my radiator and I forgot what wires these went to... 
sorry again and thanks for your time!


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