Show full size 924Board.org
Discussion Forum of 924.org
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
 Technical FAQ924 FAQ (Technical)   Technical924 Technical Section   Jump to 924.org924.org   Jump to PCA 924 Registry924 Registry

My 924 Turbo, engine done :(
Goto page Previous  1, 2, 3 ... 15, 16, 17
 
Post new topic   Reply to topic    924Board.org Forum Index -> Performance Upgrades
View previous topic :: View next topic  
Author Message
safe  



Joined: 18 Mar 2017
Posts: 319
Location: Sweden

PostPosted: Tue Aug 17, 2021 7:15 am    Post subject: Reply with quote

Never been to the GTR track. Need to visit there some time as its so close. I've got my 911 targa sort of ready to go, that hasn't gotten any track use this year.

Sad to hear about the leakage. Can you pressurise one cylinder at a time and see which one leaks out to the coolant?
Is a cracked head common or heard of?
_________________
/Magnus, Stockholm Sweden
=======================
Porsche 924 -79 NA, under EFI and turbo conversion
Back to top
View user's profile Send private message
Cedric  



Joined: 27 Aug 2004
Posts: 2202
Location: Sweden

PostPosted: Tue Aug 17, 2021 7:58 am    Post subject: Reply with quote

morghen wrote:
Looks pretty angry from that video.
Too bad it goes back to sleep so soon.
Can you x-ray your old head at work? perhaps you can find the crack..or rule it out.


Would be nice to rule out any cracks, but im not fully sure how, im not sure i have any contacts than can do x ray. I have only acess to simpler spray methods.
_________________
1980 924 Turbo
Back to top
View user's profile Send private message MSN Messenger
Cedric  



Joined: 27 Aug 2004
Posts: 2202
Location: Sweden

PostPosted: Tue Aug 17, 2021 8:00 am    Post subject: Reply with quote

safe wrote:
Never been to the GTR track. Need to visit there some time as its so close. I've got my 911 targa sort of ready to go, that hasn't gotten any track use this year.

Sad to hear about the leakage. Can you pressurise one cylinder at a time and see which one leaks out to the coolant?
Is a cracked head common or heard of?


Its worth a shot, like a car meet and some driving at the same time, and they have good pizza nowdays. Were actually planning on doing Arlanda but the event was canceled. Tell me when your going and i will tag along !

I put a camera down the cylinders, and i could find drops down in cylinder 4 (the same that had water intrusion before), thats not a good sign. Cracked heads is not very common, only if some severe overheating had been present, which it hasnt as far as i know.
_________________
1980 924 Turbo
Back to top
View user's profile Send private message MSN Messenger
safe  



Joined: 18 Mar 2017
Posts: 319
Location: Sweden

PostPosted: Tue Aug 17, 2021 6:56 pm    Post subject: Reply with quote

Cedric wrote:

Its worth a shot, like a car meet and some driving at the same time, and they have good pizza nowdays. Were actually planning on doing Arlanda but the event was canceled. Tell me when your going and i will tag along !

I put a camera down the cylinders, and i could find drops down in cylinder 4 (the same that had water intrusion before), thats not a good sign. Cracked heads is not very common, only if some severe overheating had been present, which it hasnt as far as i know.


I'll see next week maybe if the weather is good or later in September.

Not a good sign that it's the same cylinder... You had both the head and block decked so you know that they are flat?
_________________
/Magnus, Stockholm Sweden
=======================
Porsche 924 -79 NA, under EFI and turbo conversion
Back to top
View user's profile Send private message
Cedric  



Joined: 27 Aug 2004
Posts: 2202
Location: Sweden

PostPosted: Wed Aug 18, 2021 10:10 pm    Post subject: Reply with quote

safe wrote:
Cedric wrote:

Its worth a shot, like a car meet and some driving at the same time, and they have good pizza nowdays. Were actually planning on doing Arlanda but the event was canceled. Tell me when your going and i will tag along !

I put a camera down the cylinders, and i could find drops down in cylinder 4 (the same that had water intrusion before), thats not a good sign. Cracked heads is not very common, only if some severe overheating had been present, which it hasnt as far as i know.


I'll see next week maybe if the weather is good or later in September.

Not a good sign that it's the same cylinder... You had both the head and block decked so you know that they are flat?


Only the head since the rest of the engine was still in the car, maybe it wasnt enough for some reason. Who knows exactly what this engine has been through before i got it, it was in a race car for a couple of seasons, and before that im not sure
_________________
1980 924 Turbo
Back to top
View user's profile Send private message MSN Messenger
safe  



Joined: 18 Mar 2017
Posts: 319
Location: Sweden

PostPosted: Wed Aug 18, 2021 10:23 pm    Post subject: Reply with quote

Cedric wrote:
safe wrote:
Cedric wrote:

Its worth a shot, like a car meet and some driving at the same time, and they have good pizza nowdays. Were actually planning on doing Arlanda but the event was canceled. Tell me when your going and i will tag along !

I put a camera down the cylinders, and i could find drops down in cylinder 4 (the same that had water intrusion before), thats not a good sign. Cracked heads is not very common, only if some severe overheating had been present, which it hasnt as far as i know.


I'll see next week maybe if the weather is good or later in September.

Not a good sign that it's the same cylinder... You had both the head and block decked so you know that they are flat?


Only the head since the rest of the engine was still in the car, maybe it wasnt enough for some reason. Who knows exactly what this engine has been through before i got it, it was in a race car for a couple of seasons, and before that im not sure


I checked a block with a straight edge and it was a smidge low between two cylinders so I think it can happen, specially with an MLS that wants a really flat and smooth surface.
_________________
/Magnus, Stockholm Sweden
=======================
Porsche 924 -79 NA, under EFI and turbo conversion
Back to top
View user's profile Send private message
peterld  



Joined: 10 Dec 2006
Posts: 860
Location: Noosa Heads QLD Australia

PostPosted: Thu Aug 19, 2021 11:14 pm    Post subject: Reply with quote

Cedric
Did you pressure test the radiator/the cylinders/check head tension?

When you pull the head, it can be checked for cracks, etc by your head guy with chemical and black light, if x-ray is not available.
Check straightness of block with a straight edge. FSM gives tolerances.

Despite what forums espouse, MLS gaskets require nothing more than straight surfaces, cleanliness, and correct torque. Hundreds of thousands of Chev V8s have them fitted.
_________________
80/81 932/8 ROW
Back to top
View user's profile Send private message Send e-mail
MikeJinCO  



Joined: 08 Jun 2010
Posts: 1065
Location: Maysville, Colorado

PostPosted: Fri Aug 20, 2021 12:16 am    Post subject: Reply with quote

On installing Cometic head gaskets I found out the hard way. When torquing down my motor guy said to torque to about 60ft-lb, then back off about 1/3-1/2 turn then re-torque to required amount. Shouldn't need re-torque after that, but i recheck anyway. With the multi layer they compress quite a bit. Some of the local circle track guys even reuse the gaskets successfully.
_________________
Mike
Poco a Poco, #033 '78 Vintage racer, SCCA Dp-81
'77 924
cricketdesigns.com
Back to top
View user's profile Send private message Visit poster's website
Cedric  



Joined: 27 Aug 2004
Posts: 2202
Location: Sweden

PostPosted: Fri Aug 20, 2021 12:27 am    Post subject: Reply with quote

peterld wrote:
Cedric
Did you pressure test the radiator/the cylinders/check head tension?

When you pull the head, it can be checked for cracks, etc by your head guy with chemical and black light, if x-ray is not available.
Check straightness of block with a straight edge. FSM gives tolerances.

Despite what forums espouse, MLS gaskets require nothing more than straight surfaces, cleanliness, and correct torque. Hundreds of thousands of Chev V8s have them fitted.


Havent done that much testing, except for seing water drops in the bore, and measuring Co2 in the coolant. And of course the swollen collant tank/discoloured coolant. The latter is how i saw it last time, then it was obvious that the pressure had blown straight through the head gasket, which had started to disintegrate.

I have crack indication paint at work which i might use to check the head when it comes of, just to be sure and try to understand. Though a really good straight edge would be nice to have to properly check the block aswell.

The Cometic gaskets dont exactly have a flawless reputation, especially when it comes to leakage of fluids. OEM MLS gasket like modern engine uses seems much better, obviously they have massively more budget and know how... Actually, a decade ago i developed some MLS gaskets for turbo flanges at the OEM i worked at, that one have been produced in hundreds and thousands of HD trucks by now

Hopefully it will be clear why it leaked (non flat block surface for example), so i can fell safe putting another one in there on next engine..
_________________
1980 924 Turbo
Back to top
View user's profile Send private message MSN Messenger
Mike9311  



Joined: 14 Dec 2004
Posts: 1173
Location: Chicago-ish

PostPosted: Wed Sep 15, 2021 11:17 pm    Post subject: Reply with quote

Sorry to hear all this Cedric. I know how something like this feels

Maybe this helps

I have been building a temporary motor for the CS and want to use an MLS which took surprisingly long to get. Ordered at the start of May and didn't receive until July. This motor was from another crashed car I bought for parts and had super recent head work done (moly still on the aftermarket regrind cam).

The spare motor had the block deck hand brushed / wire wheeled by the PO. This made everything look rounded off around the cylinders. Straight edge, or the sweeping procedure I describe below, showed it straight overall but it wasn't in individual areas

The point here is, if it helps you at all, it is theoretically possible to deck/clean up the block while assembled. I decided to try to see if I could use the oil pan mating surface for reference. It was placed on set up blocks and swept in the Y and X axis with an indicator. It was near perfect. Well under 0.001 inch the full length. I was able to carefully skim a minimal amount off the block to clean the PO's handiwork.

I know people reuse MLS but they don't recommend reuse at least in some presentations I've seen


_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    924Board.org Forum Index -> Performance Upgrades All times are GMT + 10 Hours
Goto page Previous  1, 2, 3 ... 15, 16, 17
Page 17 of 17

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group