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06-08-2016, 04:55 PM
#16
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Hi all, a few updates today from the garage sorting my car.
Head has come back from testing and it's ok - no leaks or cracks. But. The head has had its last skim and is not tall enough for another skim.
No4 piston looks as though it's overheated - blued. (can you tell without taking the piston out?)
Measuring the deck shows No4 to be lower than the rest - indicating a bent rod.
The turbo was pressure tested and the water jacket was found to be leaking.
The mechanic wanted to know why the head gasket blew from the piston outwards.
His theory is that the turbo water jacket failed, water was ingested by the turbo and fed to the combustion chamber, traditionally the weakest part of the head gasket - No4 rearwards - blew. No4 piston hydrauliced and bent the rod.
It has been suggested that because the head is beyond skimming, the valves could be recessed to regain clearance. What is the general consensus on this?
So that's:
A new head or machining the existing head
New main bearings - because it's prudent after a HG failure.
New big end bearings - because the sudden stop of the hydraulicing can cause a 'flat'.
New piston.
New rod.
New rings.
Gaskets and belts.
Tensioner and thermostat.
..and either: a new turbo or a recon or bypass the water jacket altogether.
This whole saga has turned from what I thought was a fairly straightforward head gasket failure to an expensive engine (mostly) rebuild. The 944's garage mate is a Lotus Elan, you know, the unreliable Twin Cam engined self destructing 48 year old kit car. Well to be honest, I'd drive that car to the South of France tomorrow, but the Porsche, I'd worry taking it to the shops.
I need my faith restored.
ps. Sherry66 - tell me more about the head in your loft.
Head has come back from testing and it's ok - no leaks or cracks. But. The head has had its last skim and is not tall enough for another skim.
No4 piston looks as though it's overheated - blued. (can you tell without taking the piston out?)
Measuring the deck shows No4 to be lower than the rest - indicating a bent rod.
The turbo was pressure tested and the water jacket was found to be leaking.
The mechanic wanted to know why the head gasket blew from the piston outwards.
His theory is that the turbo water jacket failed, water was ingested by the turbo and fed to the combustion chamber, traditionally the weakest part of the head gasket - No4 rearwards - blew. No4 piston hydrauliced and bent the rod.
It has been suggested that because the head is beyond skimming, the valves could be recessed to regain clearance. What is the general consensus on this?
So that's:
A new head or machining the existing head
New main bearings - because it's prudent after a HG failure.
New big end bearings - because the sudden stop of the hydraulicing can cause a 'flat'.
New piston.
New rod.
New rings.
Gaskets and belts.
Tensioner and thermostat.
..and either: a new turbo or a recon or bypass the water jacket altogether.
This whole saga has turned from what I thought was a fairly straightforward head gasket failure to an expensive engine (mostly) rebuild. The 944's garage mate is a Lotus Elan, you know, the unreliable Twin Cam engined self destructing 48 year old kit car. Well to be honest, I'd drive that car to the South of France tomorrow, but the Porsche, I'd worry taking it to the shops.
I need my faith restored.
ps. Sherry66 - tell me more about the head in your loft.
06-08-2016, 05:15 PM
#17
Sorry to hear about your woes SadLotus.
These cars were and arguably are super cars and unfortunatly at this age they will start to cost money.
If you loose faith all together - I will be keen to buy your car - and that just goes to show that these cars are worth keeping on the road.
The money you shell out for the rebuild will be easliy reclaimable when you sell the car. The prices of good unmolested versions of the 944 turbo are climbing fast. They are out of my league and I am a genine Porsche fan with a healthy income. The fact is that i have owned two 944 turbos and bought both for less than £5k each and sold for about the same around 5 years ago.
These cars are worth £15k now.
Keep going. It is worth it.
P.S. I work in the defence and security industry - I was concerned to read about a head in the loft
These cars were and arguably are super cars and unfortunatly at this age they will start to cost money.
If you loose faith all together - I will be keen to buy your car - and that just goes to show that these cars are worth keeping on the road.
The money you shell out for the rebuild will be easliy reclaimable when you sell the car. The prices of good unmolested versions of the 944 turbo are climbing fast. They are out of my league and I am a genine Porsche fan with a healthy income. The fact is that i have owned two 944 turbos and bought both for less than £5k each and sold for about the same around 5 years ago.
These cars are worth £15k now.
Keep going. It is worth it.
P.S. I work in the defence and security industry - I was concerned to read about a head in the loft
06-09-2016, 05:28 AM
#18
Head is still available. Head was skimmed within the last 1000 miles of use as I have a receipt for work but no mention if the guides were done. All the ceramic is intact on the exhaust outlets. The head is well within spec according to the wear indicator on the face.
I bought the car with this head on it with a promax level 3 kit installed but have just installed a 3 litre turbo.
I should be able to get to the head the weekend so can post some photos for you if you are still interested . I think there is a new head gasket for it as well I can throw in.
Why are you getting a new tensioner ? Yours should be serviceable, if not I have a refurbed one here of an S2.
Simon
I bought the car with this head on it with a promax level 3 kit installed but have just installed a 3 litre turbo.
I should be able to get to the head the weekend so can post some photos for you if you are still interested . I think there is a new head gasket for it as well I can throw in.
Why are you getting a new tensioner ? Yours should be serviceable, if not I have a refurbed one here of an S2.
Simon
06-09-2016, 05:14 PM
#20
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Yes please Simon, still interested. Pictures and a price would be good.
Going to talk to garage tomorrow about the tensioner and how they can tell the piston has overheated without removing it.
Also, is there a difference between an early and a late head? The heads I see for sale all seem to be 86/87 - mine is a 91.
Going to talk to garage tomorrow about the tensioner and how they can tell the piston has overheated without removing it.
Also, is there a difference between an early and a late head? The heads I see for sale all seem to be 86/87 - mine is a 91.
06-10-2016, 06:43 AM
#21
Ok, will send some pictures across tomorrow afternoon when I can get to the head.
This head is from an 86 turbo , but as far as I am aware there are no differences between early and late cars.
Simon
This head is from an 86 turbo , but as far as I am aware there are no differences between early and late cars.
Simon
06-10-2016, 06:51 AM
#22
Also, if you are that far into the engine , I think it would be prudent to change all the conrods for forged aftermarket. After a recent rebuild I had one of the Rarst rods come through the pan in pieces. I have used PPM rods in my two recent builds which seem to be holding up well and these came in at a very reasonable price including postage from Australia.