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Audi 5000: 1984-1988, 100, 200: 1989-1991 (C3) Cylinder head overhaul


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Last Post: Sep 17, 2013 10:21 PM Last Post By: AudiDreamer
AudiDreamer

Posts: 5
Registered: 10/04/05
Cylinder head overhaul
Posted: Aug 29, 2013 4:31 AM
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Hello everyone I have an 88 Audi 100 10V and want to do a head overhaul since the engine is burning oil and smoking quite a bit, it also ticks a lot from the top end especially when cold. Are there any tips for removing and refitting these heads. I intend to buy a cylinder head gasket set and 10 x hydraulic lifters together with a cam belt, idler pulley and water pump. Do I need to replace the head bolts? Have I missed anything out?
I'm hoping that the fault lies in the head and not the block. Would a compression test be worthwhile seeing as the head needs to come off anyway?
Thanks for any help and guidance you can give.
budpalumbo

Posts: 1,454
Registered: 12/09/03
Re: Cylinder head overhaul
Posted: Aug 29, 2013 10:01 AM   in response to: AudiDreamer in response to: AudiDreamer
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A compression tester can't tell where the loss of pressure is coming from, only that you have one. What you need is a differential pressure tester. It has an air supply going into it, and a regulator to put air into the individual cylinders when each is at tdc. The difference between the two gauges on it shows the amount of loss, and you can listen for the escaping air to see where the problem is. Out of the throttle body= intake valve. Exhaust = exhaust valve. OIl cap, piston rings, radiator cap, head gasket.

If the engine smokes on start, it is probably valve guides and seals. If it always smokes, its probably the rings.

Another option is to get a vacuum gauge. It should come with or you can find resources online to explain the readings. It can be a great tool to pinpoint engine mechanical issues as well.

If the head bolts are "bolt to x torque plus x degrees, they should be replaced, however, I have reused bolts on that engine type before with no problems.
AudiDreamer

Posts: 5
Registered: 10/04/05
Re: Cylinder head overhaul
Posted: Aug 30, 2013 7:42 AM   in response to: AudiDreamer in response to: AudiDreamer
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Many thanks for the reply bud. I'll have to look into getting a leak down test done. I have however now got the option of another engine from a similar car. So I have a KU motor and now have another car with a KV engine I can swap in. Would this present any problems. Cars are 86 and 87 and both engines look very similar. Would the electronics match so I can put the KV engine into the KU car?
AudiDreamer

Posts: 5
Registered: 10/04/05
Re: Cylinder head overhaul
Posted: Sep 17, 2013 9:36 PM   in response to: AudiDreamer in response to: AudiDreamer
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I've now done a compression test of the engine and these are the figures (psi) I get with a warm engine, throttle open, 10 second crank. First dry them with a squirt of oil in the cylinders then finally without the oil:

Cyl Dry Oil Dry
1 - 185 193 187
2 - 166 178 175
3 - 180 203 200
4 - 178 203 194
5 - 180 198 190

I also carried out a vacuum test and got these results with a warm engine at idle; 17 In. Hg steady and blipping the throttle caused a rapid fall to zero and fast recovery to 22 and then back down to 17 steady.

Edited by: AudiDreamer on Sep 17, 2013 9:36 PM

Edited by: AudiDreamer on Sep 17, 2013 10:19 PM

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