Cylinder and Head Seals questions
10-10-2012, 07:29 PM
#1
Racer
Thread Starter
Cylinder and Head Seals questions
My car was built in October '90 and is considered a '91 model.
I am in the process of doing a top end rebuild and I believe this is the first time the engine has been apart. There were no seals between the barrels and head.
My question is when did Porsche decide to include the cylinder and head seals/gaskets?
I am told that it is not possible to add seals/gaskets to my engine unless I want to upgrade to later model cylinders and heads-is this true?
I am in the process of doing a top end rebuild and I believe this is the first time the engine has been apart. There were no seals between the barrels and head.
My question is when did Porsche decide to include the cylinder and head seals/gaskets?
I am told that it is not possible to add seals/gaskets to my engine unless I want to upgrade to later model cylinders and heads-is this true?
10-10-2012, 08:54 PM
#3
RL Technical Advisor
Actually, I think it was early-mid '92. There is a VIN# cutoff but I don't have that info offhand.
Still, its not a deal killer since we fix these all the time by machining the heads for the late sealing rings and modifying the top of the cylinders (if they are still good) to fit.
We've done over a hundred of these engines in such fashion and they are quire durable without any more leaks.
Still, its not a deal killer since we fix these all the time by machining the heads for the late sealing rings and modifying the top of the cylinders (if they are still good) to fit.
We've done over a hundred of these engines in such fashion and they are quire durable without any more leaks.
10-10-2012, 09:32 PM
#4
Racer
Thread Starter
Actually, I think it was early-mid '92. There is a VIN# cutoff but I don't have that info offhand.
Still, its not a deal killer since we fix these all the time by machining the heads for the late sealing rings and modifying the top of the cylinders (if they are still good) to fit.
We've done over a hundred of these engines in such fashion and they are quire durable without any more leaks.
Still, its not a deal killer since we fix these all the time by machining the heads for the late sealing rings and modifying the top of the cylinders (if they are still good) to fit.
We've done over a hundred of these engines in such fashion and they are quire durable without any more leaks.
I appreciate the input. Ball park figure ($) for the machining of the heads and barrels even though i am a bit far away to get you to do it.
One side of the engine and barrels are very clean but I don't know about the other side as I had badly leaking valve covers. There is a chance that neither side is leaking and i believe it was a small percentage of 964 engines that did leak.
thanks Ken
10-10-2012, 10:26 PM
#5
RL Technical Advisor
Hi Ken,
Ball park figures around $2600 USD for the whole banana. This includes a complete valve job, machining the heads for the sealing rings, machining cylinders and all the parts. A complete (all-Viton) gasket kit is extra, but needed for a top end rebuild.
You're right; only a small percentage had leaks big enough to justify new P/C's, and most was cosmetic. Still, we can fix this so it doesn't recur.
Ball park figures around $2600 USD for the whole banana. This includes a complete valve job, machining the heads for the sealing rings, machining cylinders and all the parts. A complete (all-Viton) gasket kit is extra, but needed for a top end rebuild.
You're right; only a small percentage had leaks big enough to justify new P/C's, and most was cosmetic. Still, we can fix this so it doesn't recur.
10-10-2012, 11:33 PM
#7
Drifting
"...engines that are susceptible to a cylinder head to cylinder leaking problem. The early cars were those built up to 62 M 06836, M64.01 for the manual transmission cars and 62 M 52757, M64.02 for the Tiptronic cars."
-Bruce Anderson's Porsche 911 Performance Handbook.
I missed it by ~ 180 engines - built on 30-Nov-90 but no leaks :-)
-Bruce Anderson's Porsche 911 Performance Handbook.
I missed it by ~ 180 engines - built on 30-Nov-90 but no leaks :-)
Trending Topics
10-10-2012, 11:57 PM
#8
Racer
Thread Starter
Hi Ken,
Ball park figures around $2600 USD for the whole banana. This includes a complete valve job, machining the heads for the sealing rings, machining cylinders and all the parts. A complete (all-Viton) gasket kit is extra, but needed for a top end rebuild.
You're right; only a small percentage had leaks big enough to justify new P/C's, and most was cosmetic. Still, we can fix this so it doesn't recur.
Ball park figures around $2600 USD for the whole banana. This includes a complete valve job, machining the heads for the sealing rings, machining cylinders and all the parts. A complete (all-Viton) gasket kit is extra, but needed for a top end rebuild.
You're right; only a small percentage had leaks big enough to justify new P/C's, and most was cosmetic. Still, we can fix this so it doesn't recur.
As always your knowledge is much appreciated by the forum. I will reassemble the engine without the gasket modifications but keep a close eye on the engine in the future.
Now I have the equipment (the Maxjax just makes life so much easier) I will be much more observant with regard to oil leaks etc
10-11-2012, 09:20 AM
#10
Nordschleife Master
There were actually two different sealing methods. The first was a soft gasket that filled the machined in groove, and the second is the metal crush type seal ring.
In MY Opinion, the issue of cylinder leaking is blown out of proportion. First, the engines don't leak oil out of the cylinder to head mating surface, what happens is that as the engine sits, the oil runs from the oil tank, past the oil pump and into the crankcase. Depending on how high and whether or not the car is on a level surface, this oil can rise into the cylinders and some oil may push past the oil control ring and first and second compression ring and into the cylinder where upon startup it will burn. In addition, when the engine is cold, some of the residual oil may be pushed past the cylinder to head mating surface which is the black residue seen on the underside of the engine.
Remember that the turbo engines and the 3.2 Carrera before it do not have cylinder head gaskets. Also, my racing engine that uses LN Engineering cylinders does not have any head gaskets and does not leak (although it does have very good cylinder head studs). YMMV
In MY Opinion, the issue of cylinder leaking is blown out of proportion. First, the engines don't leak oil out of the cylinder to head mating surface, what happens is that as the engine sits, the oil runs from the oil tank, past the oil pump and into the crankcase. Depending on how high and whether or not the car is on a level surface, this oil can rise into the cylinders and some oil may push past the oil control ring and first and second compression ring and into the cylinder where upon startup it will burn. In addition, when the engine is cold, some of the residual oil may be pushed past the cylinder to head mating surface which is the black residue seen on the underside of the engine.
Remember that the turbo engines and the 3.2 Carrera before it do not have cylinder head gaskets. Also, my racing engine that uses LN Engineering cylinders does not have any head gaskets and does not leak (although it does have very good cylinder head studs). YMMV
10-11-2012, 08:31 PM
#11
Burning Brakes
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There were actually two different sealing methods. The first was a soft gasket that filled the machined in groove, and the second is the metal crush type seal ring.
In MY Opinion, the issue of cylinder leaking is blown out of proportion. First, the engines don't leak oil out of the cylinder to head mating surface, what happens is that as the engine sits, the oil runs from the oil tank, past the oil pump and into the crankcase. Depending on how high and whether or not the car is on a level surface, this oil can rise into the cylinders and some oil may push past the oil control ring and first and second compression ring and into the cylinder where upon startup it will burn. In addition, when the engine is cold, some of the residual oil may be pushed past the cylinder to head mating surface which is the black residue seen on the underside of the engine.
Remember that the turbo engines and the 3.2 Carrera before it do not have cylinder head gaskets. Also, my racing engine that uses LN Engineering cylinders does not have any head gaskets and does not leak (although it does have very good cylinder head studs). YMMV
In MY Opinion, the issue of cylinder leaking is blown out of proportion. First, the engines don't leak oil out of the cylinder to head mating surface, what happens is that as the engine sits, the oil runs from the oil tank, past the oil pump and into the crankcase. Depending on how high and whether or not the car is on a level surface, this oil can rise into the cylinders and some oil may push past the oil control ring and first and second compression ring and into the cylinder where upon startup it will burn. In addition, when the engine is cold, some of the residual oil may be pushed past the cylinder to head mating surface which is the black residue seen on the underside of the engine.
Remember that the turbo engines and the 3.2 Carrera before it do not have cylinder head gaskets. Also, my racing engine that uses LN Engineering cylinders does not have any head gaskets and does not leak (although it does have very good cylinder head studs). YMMV
the first paragraph is one of the reasons why i think the car i just bought smoked for about 20 mins upon start up when i originally saw it. the car has been recently been stored in a driveway which is on a 45 degree slope.
10-11-2012, 09:18 PM
#12
Racer
Thread Starter
Cylinder and head seal questions
There were actually two different sealing methods. The first was a soft gasket that filled the machined in groove, and the second is the metal crush type seal ring.
In MY Opinion, the issue of cylinder leaking is blown out of proportion. First, the engines don't leak oil out of the cylinder to head mating surface, what happens is that as the engine sits, the oil runs from the oil tank, past the oil pump and into the crankcase. Depending on how high and whether or not the car is on a level surface, this oil can rise into the cylinders and some oil may push past the oil control ring and first and second compression ring and into the cylinder where upon startup it will burn. In addition, when the engine is cold, some of the residual oil may be pushed past the cylinder to head mating surface which is the black residue seen on the underside of the engine.
Remember that the turbo engines and the 3.2 Carrera before it do not have cylinder head gaskets. Also, my racing engine that uses LN Engineering cylinders does not have any head gaskets and does not leak (although it does have very good cylinder head studs). YMMV
In MY Opinion, the issue of cylinder leaking is blown out of proportion. First, the engines don't leak oil out of the cylinder to head mating surface, what happens is that as the engine sits, the oil runs from the oil tank, past the oil pump and into the crankcase. Depending on how high and whether or not the car is on a level surface, this oil can rise into the cylinders and some oil may push past the oil control ring and first and second compression ring and into the cylinder where upon startup it will burn. In addition, when the engine is cold, some of the residual oil may be pushed past the cylinder to head mating surface which is the black residue seen on the underside of the engine.
Remember that the turbo engines and the 3.2 Carrera before it do not have cylinder head gaskets. Also, my racing engine that uses LN Engineering cylinders does not have any head gaskets and does not leak (although it does have very good cylinder head studs). YMMV
Actually, I think it was early-mid '92. There is a VIN# cutoff but I don't have that info offhand.
Still, its not a deal killer since we fix these all the time by machining the heads for the late sealing rings and modifying the top of the cylinders (if they are still good) to fit.
We've done over a hundred of these engines in such fashion and they are quire durable without any more leaks.
Still, its not a deal killer since we fix these all the time by machining the heads for the late sealing rings and modifying the top of the cylinders (if they are still good) to fit.
We've done over a hundred of these engines in such fashion and they are quire durable without any more leaks.
The answers make be much more confident in my decisions and the time and information is greatly appreciated and to get it from such highly respected sources makes it even better.
10-15-2012, 02:46 AM
#13
Racer
Thread Starter
Cylinder and Head Seal questions
I pulled the barrels off today because we decided that having gone this far that a new set of rings was not a lot of money or labour-I could be proved wrong though about the money and labour!
When I removed the heads there were definitely no seals/gaskets between the heads and barrels but there is a green "O" ring between the barrels and the case -is this normal to have this one seal but not both? Could it be that in a earlier life that the barrels were changed to the upgraded part because of an oil leak but not the heads?
When I removed the heads there were definitely no seals/gaskets between the heads and barrels but there is a green "O" ring between the barrels and the case -is this normal to have this one seal but not both? Could it be that in a earlier life that the barrels were changed to the upgraded part because of an oil leak but not the heads?
10-15-2012, 03:41 AM
#14
RL Technical Advisor
When I removed the heads there were definitely no seals/gaskets between the heads and barrels but there is a green "O" ring between the barrels and the case -is this normal to have this one seal but not both? Could it be that in a earlier life that the barrels were changed to the upgraded part because of an oil leak but not the heads?
