7a 20v problems

8690q · 06-04-15, 12:49 PM

Hi,

My 80 20v avant is sounding poorly. It was going well then suddenly it's sounding rough and driving with little power. I say it was going well but it has been using oil and smelling a bit after a good hiding lately.
A couple of years ago I had a camshaft snap in this engine giving nearly the same symptoms as now. I checked the compression and it was down at near 0 on cylinder 2 which was what happened when the camshaft snapped except low compression was on the number 5 cylinder that time.
I've got it stripped down and the camshaft is still in one piece. Cylinder 2 valves are oily and dirty when viewed throught he intake ports.
Does this sound like a head or block problem as I'm reluctant to strip it any further till I know if I can get a head gasket as sourcing one was the biggest holdup last time.
Is an NG engine gasket the same as a 20v 7a as that would be handy seeing as Andy10v has offered me one if I need it.

PoloGaz · 07-04-15, 03:25 PM

It's a different part number in vagcat, so presumably it's a different thickness

Oily valves and no compression, very worn stem seals?

mikes2 · 07-04-15, 03:56 PM

pretty sure the 20v uses different oil / waterway paths from the 10v also

msh · 08-04-15, 12:04 AM

Quote:

Originally Posted by mikes2

pretty sure the 20v uses different oil / waterway paths from the 10v also

You should be mistaking that with some older 10v engines, so old that they are using shims, not tappets - because if we're talking about late 80's 5 pot engines, why different heads on the same engine block would be using different liquid flow paths?

PoloGaz · 08-04-15, 12:33 AM

Less likely to be a fuelling issue then with the move from the hitachis. Let us know what you find out

Been looking into the head gaskets. The 20v engines all use the same gasket with the exception of the 7a which must be because of the larger bore. how annoying! (The 2.0 20v NA uses same gasket as 20vT)

I believe the Elring part number for the gasket is 128 220

Part number for the bolts is 034103385C

What's with the spiral design? Oil supply?

8690q · 19-04-15, 08:39 PM

Wee update on this.

I got the cylinder head off today and the head gasket has blown between two cylinders.

I stuck a puddle of oil on each of the pistons to check it stays there and I'll test the valves for leaks tomorrow.

If no leaks would anything in particular cause the gasket to burn out there or just normal head gasket failure ?

If I find no leaks I would like to just get the engine back together with a new gasket as we can't work as a one car family too much longer. Anything I should be checking before getting new bolts and a gasket and sticking it back together ?

PoloGaz · 07-04-15, 05:54 PM

I've had a bit more of a think about this. Worn stem seals would mean more oil consumption/oil on the valves but not loss of compression

Could be the headgasket between the cylinder and an oil way?

I take it it's just that cylinder that looks bad?

One thing it could be is a burnt exhaust valve - what fuel injectors are you running?

Failing that, rings I guess?

8690q · 07-04-15, 10:29 PM

Thanks Gaz and thanks Mike.

I've sourced a 20v gasket set from another forum member hopefully. I'll see what state the old one is in when I get to it. Best bet going to Audi for the head bolts ?
All other valves for the other cylinders are spotless.
I'm running the uprated injector kit, the orange ones I think.
I hope it's not a ring burnt out but I'll cross that bridge when I get too it.
If I need to get the head rebuilt I think I'll treat it to a wee bit porting and polishing, the car deserves it.

07-04-15, 03:56 PM	#3
mikes2 4 ring whore! Classic Audi Club Member Join Date: Nov 2007 Location: Polmont Posts: 2,617	pretty sure the 20v uses different oil / waterway paths from the 10v also __________________ 1991 90 quattro 20v sport 1991 90 quattro

07-04-15, 03:25 PM	#2
PoloGaz Grown up member Classic Audi Club Member Join Date: Aug 2012 Location: Manchester Posts: 362	It's a different part number in vagcat, so presumably it's a different thickness Oily valves and no compression, very worn stem seals?

08-04-15, 12:33 AM	#5
PoloGaz Grown up member Classic Audi Club Member Join Date: Aug 2012 Location: Manchester Posts: 362	Less likely to be a fuelling issue then with the move from the hitachis. Let us know what you find out Been looking into the head gaskets. The 20v engines all use the same gasket with the exception of the 7a which must be because of the larger bore. how annoying! (The 2.0 20v NA uses same gasket as 20vT) I believe the Elring part number for the gasket is 128 220 Part number for the bolts is 034103385C What's with the spiral design? Oil supply?

19-04-15, 08:39 PM	#6
8690q Grown up member Classic Audi Club Member Join Date: Jun 2009 Location: Coalsnaughton Posts: 190	Wee update on this. I got the cylinder head off today and the head gasket has blown between two cylinders. I stuck a puddle of oil on each of the pistons to check it stays there and I'll test the valves for leaks tomorrow. If no leaks would anything in particular cause the gasket to burn out there or just normal head gasket failure ? If I find no leaks I would like to just get the engine back together with a new gasket as we can't work as a one car family too much longer. Anything I should be checking before getting new bolts and a gasket and sticking it back together ?

07-04-15, 05:54 PM	#7
PoloGaz Grown up member Classic Audi Club Member Join Date: Aug 2012 Location: Manchester Posts: 362	I've had a bit more of a think about this. Worn stem seals would mean more oil consumption/oil on the valves but not loss of compression Could be the headgasket between the cylinder and an oil way? I take it it's just that cylinder that looks bad? One thing it could be is a burnt exhaust valve - what fuel injectors are you running? Failing that, rings I guess?

07-04-15, 10:29 PM	#8
8690q Grown up member Classic Audi Club Member Join Date: Jun 2009 Location: Coalsnaughton Posts: 190	Thanks Gaz and thanks Mike. I've sourced a 20v gasket set from another forum member hopefully. I'll see what state the old one is in when I get to it. Best bet going to Audi for the head bolts ? All other valves for the other cylinders are spotless. I'm running the uprated injector kit, the orange ones I think. I hope it's not a ring burnt out but I'll cross that bridge when I get too it. If I need to get the head rebuilt I think I'll treat it to a wee bit porting and polishing, the car deserves it.