# 1.8t block how to check its top dead center



## 240dubb (Feb 10, 2012)

okay so i bought a block its rlly clean nd seems to be in good working order how do iknow if its top dead center , its just the block i dont have the head


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## jbutlertelecom (Aug 12, 2009)

When the piston at the front of the engine is right at it's highest point and can't go any higher (just about even with the block), that's TDC. Simple enough, right?

It's best to use the crank damper so you can line up the marks with the cover (if you have both the crank damper and the lower cover installed), otherwise you could be off a hair (should be close enough to install the head but not the timing belt until those above items are installed).


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## 87vr6 (Jan 17, 2002)

At the front? Or the left most piston jbutler?

Answer is front most if longitiudal, left most if transverse. 

Of course, since you have a bare block, when the front of the block is facing you (the side with the oil filter hosing), then use the left most piston.


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## derekb727 (Dec 22, 2007)

The side with the timing belt is the front


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## jbutlertelecom (Aug 12, 2009)

derekb727 said:


> The side with the timing belt is the front


:thumbup:

As far as I am aware, there is ONLY one "front" to an engine and it is ALWAYS the "side" with the timing belt, lol. The "rear" of an engine being the "side" that the transmission is attached. Yes, even transverse engines are this way, "transverse" being the way the "engine" is mounted in the vehicle.


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## 87vr6 (Jan 17, 2002)

I know you know, as do I, but others may not, so we clarified this here. :beer:


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## jbutlertelecom (Aug 12, 2009)

87vr6 said:


> I know you know, as do I, but others may not, so we clarified this here. :beer:


:thumbup:



:beer:


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## groggory (Apr 21, 2003)

derekb727 said:


> The side with the timing belt is the front


I learned something


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## 87vr6 (Jan 17, 2002)

groggory said:


> I learned something



See? That's why there is a rear main seal and a front main seal...


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## 240dubb (Feb 10, 2012)

what if its not top dead center ?


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## GolfCL Smooth (Jul 9, 2006)

240dubb said:


> what if its not top dead center ?


What are you trying to accomplish?
As mentioned above, get it as close as you can to TDC before putting the head on (make sure the head is TDC too) and then use the crank pulley and cover plate marks to fine-tune the timing belt.


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## 240dubb (Feb 10, 2012)

im tryin to build a motor lmao i blew mine up in my jetta so i got a 1.8t out of a 98 passat , nd now im trying to peice it together , the block is complete i jus want it tdc so that i can install the head .


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## jbutlertelecom (Aug 12, 2009)

240dubb said:


> what if its not top dead center ?


Turn the crank until it is. 
I'm curious as to why you would be building an engine if common wrenching escapes you? Perhaps you should let someone else do it for you, like a mechanic or machine shop?
Do you have a friend that's a mechanic or has at least wrenched before? It would be a sad waste of time and money to attempt this by yourself, we can't hold your hand and guarantee you won't screw something up in the process and it could become a VERY expensive endeavor...

I applaud you for trying, but... please don't take offense as there is obviously a prerequisite here, of basic mechanical aptitude.


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## jbutlertelecom (Aug 12, 2009)

240dubb said:


> im tryin to build a motor lmao i blew mine up in my jetta so i got a 1.8t out of a 98 passat , nd now im trying to peice it together , the block is complete i jus want it tdc so that i can install the head .


I'm curious, what year motor was the jetta? I ask because the block you bought is an AEB (external water pump, pre 2000, called an 058 block) motor and is not a straight swap with an internal water pump engine (2000-2006 motors, called an 06A or 06B depending on the exact year). These motors are different in many ways and are not direct swaps of each other (different in many ways, not just the water pump)


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## Mindfault (Feb 2, 2010)

Just line the crank pulley up to the mark on the cover. Easiest most accurate way


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## jbutlertelecom (Aug 12, 2009)

Mindfault said:


> Just line the crank pulley up to the mark on the cover. Easiest most accurate way


I don't think ha has the pulley or cover to do this. It's a BARE block, sans any accessories like crank pulley or covers. Pretty sure that's why he's having trouble.


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## Mindfault (Feb 2, 2010)

Possibly, but if hes going to put it together he will need these things. Also, he could use a transmission to tell where the motor is. Also, OP you could use a dial indicator. And place it on top of the block and. Watch the needle and when it stops moving up, and then starts to go down. When it stops going up its at tdc


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## 240dubb (Feb 10, 2012)

well this is my first time building ive worked on stuff b4 ive changed clutches fuel pumps 5 speed swap in a 240 but never put anything in time or anything like that i kind of figured u can jus turn the crank but i wasnt sure if that was guna mess anything up better safe than sorry


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## Mindfault (Feb 2, 2010)

Well, timing a motor and putting one together is more work than just replaceing parts. The 1st picture in this thread is tdc. You need to get the crank pulley on there so you know you're not 180* out on exhaust stroke. Now it wouldnt matter but later when you try to line up both timing marks they would never match up. Just get the crank pulley, and cam gear cover then line the 2 marks up, then youre done


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## 240dubb (Feb 10, 2012)

the lines will never match up bcuz the the head is brand new


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## Mindfault (Feb 2, 2010)

Bull****. As long as you have the cam gear match the block code it WILL match up. Dont use the cylinder heads cam gear, use the cam gear that came off a cylinder head with the blocks engine code. For example. I have a AWP block with an AEB head, and i had to use the AWP cam gear on my aeb head. 


How do you suppose it wouldnt match up?


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## groggory (Apr 21, 2003)

Mindfault said:


> Bull****. As long as you have the cam gear match the block code it WILL match up. Dont use the cylinder heads cam gear, use the cam gear that came off a cylinder head with the blocks engine code. For example. I have a AWP block with an AEB head, and i had to use the AWP cam gear on my aeb head.
> 
> 
> How do you suppose it wouldnt match up?


Just to be more specific...

There is no AWP block. There is an 06A or 06B block.

There is no AEB block. There is an 058 block.

AWP and AEB are head codes, not block codes. Use the cam gear that matches the block. There are only 2 different cam gears.

Use the timing belt that matches your block.

Use the cam trigger wheel that matches your ECU.

Use the crank trigger wheel & sensor that matches your ECU.


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## Mindfault (Feb 2, 2010)

Grog. You know what im sayin


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## jbutlertelecom (Aug 12, 2009)

You would have a VERY hard time putting a motor 180* out (the piston would be at it's LOWEST point if you were). Once the #1 piston is at it's top means you are @ TDC. Think about it...


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## Mindfault (Feb 2, 2010)

Nope. Talking about strokes. 4th cylinder could be at tdc methinks:beer:


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## Mindfault (Feb 2, 2010)

So the cranks gear mark could be facing down. When 4th cylinder would be at tdc. And 1st cylinder would be on exhaust


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## 240dubb (Feb 10, 2012)

LOL so do i do after i get the head


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## Mindfault (Feb 2, 2010)

After u get the head u put the right cam gear on then you out the head on


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## Charlie_M (Mar 23, 2011)

jbutlertelecom said:


> When the piston at the front of the engine is right at it's highest point and can't go any higher (just about even with the block), that's TDC. Simple enough, right?


It's not quite that simple, because near TDC, the crank can move quite a few degrees without much change in piston height. Even if you have a dial indicator on the piston, it's tough to get accurate crank position.

Method I used back when I did stuff like this:
* bolt a degree wheel on crank, with appropriate pointer attached somewhere.
* make, then install, a screw stop so you can stop the #1 piston about 1" below TDC
* *Gently* turn the crank until the #1 piston hits the stop; take a reading on the degree wheel
* Turn the crank back the other way, till the piston *gently* hits the stop again; take another reading
* remove the screw stop
* Look at the degree wheel, and split the two previous readings; turn the crank to that point and it's at TDC

May sound complicated, but it's pretty easy and doesn't need machinists tools. Easily get the crank within a half degree or better of TDC


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## Charlie_M (Mar 23, 2011)

Mindfault said:


> Nope. Talking about strokes. 4th cylinder could be at tdc methinks:beer:


No, the block, crank and piston don't know anything about being on the firing or exhaust stroke. That's set by the head timing alone.


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## jbutlertelecom (Aug 12, 2009)

Charlie_M said:


> No, the block, crank and piston don't know anything about being on the firing or exhaust stroke. That's set by the head timing alone.


Exactly!

Someone else "get's it", finally put this misconception to rest...

:thumbup:

:beer:


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## jbutlertelecom (Aug 12, 2009)

Charlie_M said:


> It's not quite that simple, because near TDC, the crank can move quite a few degrees without much change in piston height. Even if you have a dial indicator on the piston, it's tough to get accurate crank position.
> 
> Method I used back when I did stuff like this:
> * bolt a degree wheel on crank, with appropriate pointer attached somewhere.
> ...


I think you are over complicating it for "general rule of thumb". I doubt anyone running stock or slightly modified will require this kind of accuracy. That's why I didn't mention it in the first place. While I agree that simply putting the piston @ it's highest point is not 100%, it IS close enough to start assembling things until you get ready to put the timing belt on, by then you will have the lower cover and crank pulley on and can use those for final adjustment. Remember that when the cams are set to the windows the #1 and #4 valves are all closed (both intake and exhaust) so there is no worry for damage when placing the head.
Thanks for explaining to the noobs out there how the "pro's" do it though.

:beer:


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