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Timing belt change/head gasket change time questions!
by
Topherdiesel
on 16 Sep, 2004 06:31
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So I need to chage my timing belt, as well as replace a leaky headgasket.
SO I ask you gents this...
how is changing a timing belt/headgakste different on a diesel than on a gas engine.
How afraid do I need to be, or do I just mark the position of all of the pulleys(crank, cam, injection pump) and I should be fine on re-installation??
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#1
by
Rat407
on 16 Sep, 2004 09:11
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If I can do it anybody can do it.
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#2
by
Topherdiesel
on 17 Sep, 2004 05:24
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I have the HAYNES manual?
Wondering what kind of special tools I all need.
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#3
by
racer_x
on 18 Sep, 2004 08:02
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Timing is critical on the diesels. Especially the cam timing. The valves come within 0.020" (0.5mm) of the pistons in normal operation if everything is right. There's not a lot of margin for error there.
You'll need a cam locating fixture to hold the cam (a piece of angle stock works OK as a substitute), and you'll need a pin to hold the injection pump (a deep well socket of the appropriate size works).
I haven't read the Haynes book on changing the diesel timing belt. I would recommend getting the Bentley service manual. It goes into detail about the job.
One thing that's a little different from the gassers is the cam sprocket. There's no key in the diesel. You have to loosen the cam bolt slightly with the fixture holding the cam and whack the sprocket with a rubber hammer, then tighten the bolt back up. That's how you get the cam timing exactly right (not 1/2 tooth off).
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#4
by
veritas137
on 19 Sep, 2004 15:23
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I've got a Bentley manual and have been trying to pick up the proper tools on ebay. I need to do a headgasket replacement and was quoted anywhere from $800 to $1300. :cry:
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#5
by
chrissev
on 23 Sep, 2004 20:15
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I've got a Bentley manual and have been trying to pick up the proper tools on ebay. I need to do a headgasket replacement and was quoted anywhere from $800 to $1300. :cry:
Head gasket replacement is easy. And replace the belt and tensioner while you're at it. I've found that you can get the engine back in time again just by marking the old belt and then matching it up with the new belt. My theory was that, when the old belt was new, it was put on the engine and the engine was timed. Since then, the pump timing may have been tweaked a bit, but the set up of the other timed parts would not have been touched. So the new belt, being as the old belt was when it was new, would go right on in perfect time and I would just have to tweak the pump a bit. I tried this (marked the location of the old belt on the various pulleys, then marked the belt, then transfered the marks from the old belt to the new belt and put the new belt on where the old one was). I then timed the pump (you use a dial gauge and turn the engine backwards until you get the reading you want, then turn the pump to time it). Then I started it up and it ran perfectly.
I don't know why they quote you so much to replace the gasket. The hardest part of the job is getting the head and block surface clean. The rest is just simple work. And it's not even that complicated really. It's one of the great mysteries I've encountered, why mechanics charge so much to replace head gaskets.
Coincidentally, if you have an old VW diesel with a large oil leak down the front of the engine block, coming from the head gasket, and you are going to take the head off to replace the gasket, replace the rings as well. Otherwise you will need to do this maybe 10,000km down the road. Trust me.
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#6
by
veritas137
on 23 Sep, 2004 20:20
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Thanks for the info. I will be keeping the old belt on since it is only about 10k miles old anyways.
Part of the reason the cost is so high is that mk2 diesel's weren't sold out here so finding a mechanic is a bit difficult and most don't even want to do it out of fear of screwing it up.
Big diesel meet this weekend, gonna talk to some folks and maybe find someone who has done it before and will help me out.
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#7
by
chrissev
on 23 Sep, 2004 20:25
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So I need to chage my timing belt, as well as replace a leaky headgasket.
SO I ask you gents this...
how is changing a timing belt/headgakste different on a diesel than on a gas engine.
How afraid do I need to be, or do I just mark the position of all of the pulleys(crank, cam, injection pump) and I should be fine on re-installation??
How is it different?: diesel is interference. The pistons can hit the valves if you don't time it right. I've done it by marking everything. Some people say you shouldn't do this. I guess if you want to be ultra safe you should re-time everything and get it all aligned, but I figure if the old belt is that much different in size from the new belt, then wouldn't the pistons have been hitting the valves already?
you need a few special tools to do the job. You can make them all yourself, except for the dial gauge to time the pump when you're done, which has to be purchased. You need a gauge that reads from .001" to 1.0" and that has a long extension shaft to go into the pump. There is a procedure for timing it that is in the Bentley manual for sure and might be in Haynes but I'm not 100% sure of that. I don't recommend Haynes and would go with Bentley if you have the money as it is a better manual by far.
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#8
by
chrissev
on 24 Sep, 2004 06:49
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Thanks for the info. I will be keeping the old belt on since it is only about 10k miles old anyways.
Part of the reason the cost is so high is that mk2 diesel's weren't sold out here so finding a mechanic is a bit difficult and most don't even want to do it out of fear of screwing it up.
Big diesel meet this weekend, gonna talk to some folks and maybe find someone who has done it before and will help me out.
Yeah, I did it first time on my old 79 rabbit and the only problem I had was one bolt wouldn't come out and I almost stripped it b/c the hex head tool I was using I had fabricated myself (with a file using a hex head tool of a different size) b/c I couldn't find one the right size that would fit in the head bolt holes. The newer heads all have the star head bolts (not torx) that are stretch bolts (throw them away and buy new ones) and you get a star head tool from snap on that will take them out (costs around $50 I think - I have one in my tool box). There is a sequence for loosening and tightening the bolts that has to be followed so you don't warp the head. You have to drain the coolant. You should try not to drop any sh*t down the various holes in the engine block because it will get into your engine and (like what happened to me) get into your water pump bearing and screw it up (necessitating a new water pump). If you have a turbo on your head you will find it very difficult to center the head on the gasket because of the weight of the turbo. It's best to have two people and maybe some long rods to center the head as you're not supposed to move it at all on the gasket or you will scratch the gasket surface. That's all I can think of. Remember also to tap out the holes in the head before you put the new bolts in and torque the bolts on installation and again I think 1000km after installation per factory specs (in the Bentley manual). Also get the right gasket (or you can easily destroy your cylinder head). If the engine is stock and the head has not been machined I think it is a four notch gasket.
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#9
by
maxt
on 11 Dec, 2006 08:48
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i am reading this thread and just realizd i forgot to mark the cam pulley before removing it..since it isnt keyed, im kinda worried im not going to get it on 100% right.(could be 1/2 tooth off)..any tricks for that one?
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#10
by
Baxter
on 11 Dec, 2006 10:08
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i am reading this thread and just realizd i forgot to mark the cam pulley before removing it..since it isnt keyed, im kinda worried im not going to get it on 100% right.(could be 1/2 tooth off)..any tricks for that one?
Put it to TDC on the crank.
Use the setting bar in the back of the cam, this sets it to TDC.
Peg the pump pulley.
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#11
by
burn_your_money
on 11 Dec, 2006 13:21
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Remember also to tap out the holes in the head before you put the new bolts in and torque the bolts on installation and again I think 1000km after installation per factory specs (in the Bentley manual). Also get the right gasket (or you can easily destroy your cylinder head). If the engine is stock and the head has not been machined I think it is a four notch gasket.
Mk2s only have up to a 3 hole gasket. I think around 1981 when VW stopped using the 11mm head bolts they switched their gaskets as well. Just buy what you have on there.
Correct me if I'm wrong, but isn't head work negligable? and you only need to worry about the gasket thickness if you do work to the block, IE shaving it, new pistons etc?
I've done 2 headgasket jobs so far on a diesel (actually I've never done it on a gasser) The first one worked well for 150 kms, then the gasket crapped out on me. That was my fault though for not checking to make sure the head was straight. It was warped so of course the gasket didn't last.
I just did my second one last week, on a differant car.
I reuse 4 of my head bolts. I take 2 of them and cut their heads of and then put a slot in the top of them. I install these into the block and then use them as guides for placing the head on. Just be very careful not to hit the bottom of the head on the bolt heads.
The other 2 I cut 4 slits all the way down them with a dremel and then make an X on the bottom. I use this as my tap. It works perfectly for getting any fluids out of the holes.
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#12
by
LeeG
on 11 Dec, 2006 22:17
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The relationship of the campulley to the cam is not important. The critical points are what Mr Brick-Yard notes above: setting the crank, camshaft and IP to their respective TDC marks Next leave the cam pulley loose to rotate, install the belt, tension it and then torqe up the cam bolt.
Then rotate it by hand for a couple complete rotations to check that it does rotate and settle the belt, check tension and then set the IP timing.