Parts Catalog Accessories Catalog Tech Info Tech Forums
 
  Search our site:    
 Cart  | Project List | Order Status | Help    
Go Back   Pelican Parts Technical BBS > 1- Porsche Technical Forums > Porsche 924/944/968 Technical Forum

Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Mein Gott!
 
Panzer909's Avatar
 
Join Date: Oct 2000
Location: Pittsburgh, PA USA
Posts: 1,520
Garage
What causes cracked heads & blown head gaskets?

Last week, a friend of mine developed an engine problem where its eating coolant and we're suspecting either a cracked cylinder head and/or head gasket. The car already had a new gasket job about four years ago, and he takes religious care of it. He never overheated it or anythuing like that.

It got us to thinking - exactly what is the main cause of a blown head gasket? It takes an awful lot to crack a cylinder head, so is there a sure fire way that this happens beside age?
__________________
Johnny
1987 944S
1984 944 (R.I.P.)
1972 Triumph TR6 - 100% trouble free between breakdowns
2003 BMW 325xi
Old 12-14-2004, 06:50 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #1 (permalink)
Registered User
 
Join Date: Dec 2004
Location: Harrisonburg, Alexandria, Va.
Posts: 465
Send a message via AIM to AznDrgn
pretty much overheating and things hitting the head are the main cuases of cracked cylinder heads. Head gasket failure however could just be bad installation, cheap gasket, or high compression either by forced induction, nitrous, or pistons.

Are you sure it's a head gasket? does the car blow white smoke? is there water in the oil or oil in the water?
__________________
'91 Jeep Cherokee 4.0L HO - Daily driver
'83 Callaway 944 2.5L turbo - Soon to be daily driver
'83 Porsche 944 NA - sold
'78 Porsche 924 NA- RIP
'89 Porsche 944 S2 - Parted

Looking for a nice 944S for a daily driver.
Old 12-14-2004, 07:33 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #2 (permalink)
Registered User
 
Join Date: Nov 2003
Location: Charlotte NC
Posts: 1,197
Wel...if its not overheating, and not blowing white smoke, then you propbably have a leak somewhere. I had one 944 that went trough coolant like nobodys biz...But I caould never find coolant under the car.

Turns out it was a bad pressure cap causing it to spit teh coolant out while I was driving...My wife was behind me when it happened. Got coolant all over the BMW.
__________________
Current: 1973 914/4 project. FOR SALE
Old 12-14-2004, 07:54 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #3 (permalink)
Registered User
 
TCMdocs944's Avatar
 
Join Date: Dec 2002
Location: St. Petersburg, Florida
Posts: 1,990
Heat.

The only thing preventing faster speeds, long space travel, unlimited production of energy...the list goes on...

is that all of these things produce heat which causes things to bend, crack and deteriorate.


I am currently working on a cold-fusion reactor for my 944. When I get done I will give you guys the plans.















Uhhh, overtorque plus heat can definately cause something to break.
__________________
83 944 white w/Boxster wheels
Planned mods- custom leather interior, 968 antenna, soundsystem, 968 style rockers, clear sidemarkers
Old 12-14-2004, 08:42 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #4 (permalink)
Administrator
 
Z-man's Avatar
 
Join Date: Feb 2001
Location: NJ, USA
Posts: 8,185
Garage
A couple of years ago, I lost my H2O pump while driving at the track. As soon as the temp guage went to red, I shut the car down immediately. I actually drove the car home from the track (4 hour ride) and over-heated once more, but again, I shut it down right away.

Could that have been the start of a small crack on my head? Perhaps.

This summer I developed a situation where the coolant was leaking into the head quite dramatically on the track. I was adding close to a gallon of coolant/water to the system when driving on the track. In street driving, while I did have to add some water, it wasn't as significant. Kept an eye on the temp guage, but it never went too hot, even on the track. Throughout the summer, my mechanics tried everything - replaced seals, bypassed the coolant passages flowing through the throttle body....all the 'easy & cheap' stuff. Still, the problem persisted.

Finally in August, my oil pressure sender unit got fouled due to all the water in there, and the car lost oil pressure. At that point, the head came off. The head gasket was a mess, but didn't really show any signed of where water was getting into the cylinders. The head was magnafluxed, and a small crack was indeed found above the #2 cylinder. So small is the crack that you cannot see it.

What caused my head to crack? I suspect a combination of the following:
1. The loss of my H2O pump a couple of years ago, and the subsequent overheating, even though I didn't drive it once it got in the red.
2. The fact that I'm pushing my car while on the track - I'm at or near redline for 20 minutes at a time!
3. My engine has 150,000 miles on it. And while I've only had my car for 30,000 of those miles, that is still a lot of wear and tear on a motor.

Just my thoughts,
-Z.
__________________
1989 944S2 - June, 2001 - January, 2014

Visit my homepage!
<><
Old 12-14-2004, 08:46 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #5 (permalink)
Registered User
 
Join Date: Aug 2000
Location: Corpus Christi, TX
Posts: 321
was the head torqued down correctly when the head gasket was replaced?

Improper sequence can warp heads, cause cracking, blow gaskets, etc.
__________________
1987 944S, needs crank work
1992 Jeep Sahara YJ 4.0
2001 Harley FXST
1981 VW Rabbit diesel
1984 Isuzu P'up diesel
Old 12-14-2004, 09:20 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #6 (permalink)
 
Now available:  101 Projects for Your Porsche Boxster!
Mein Gott!
 
Panzer909's Avatar
 
Join Date: Oct 2000
Location: Pittsburgh, PA USA
Posts: 1,520
Garage
Hmm. We are not 100% certain that its the gasket or crack in the head, but its pointing in that direction fast. We're doing all the "easy" possibilities so far - replaced cap, went over it at high idle for external leaks, and he even did the oil cooler seals last month.

In looking at his records, the head was removed and even had machine work four years ago. This was right before he bought it. We're not sure about their process (torqing it correctly, etc.) but:

1. It needs topped up with coolant about every 1 1/2 weeks or so with NO external leaks. I even checked the infamous heater valve deep in the engine bay.

2. There's no plume of smoke from the exhaust (other than the fact that its really cold here in PA now).

3. The car drives/idles/accelerates fine and always has.

4. The oil looks fine when drained and no real sign of milkshake.


I'm just deducing that the problem is something REALLY bad. A search for previous threads on coolant loss point to cylinder head issues. We just don't know what he's gonna do.............
__________________
Johnny
1987 944S
1984 944 (R.I.P.)
1972 Triumph TR6 - 100% trouble free between breakdowns
2003 BMW 325xi
Old 12-14-2004, 11:15 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #7 (permalink)
Registered User
 
ae1969's Avatar
 
Join Date: Jul 2001
Location: Edmonton, Alberta, Canada
Posts: 4,528
Send a message via ICQ to ae1969
How about a compression test and/or leak down and the mystery will be solved.
__________________
Alex - PCA Polar Region - Boxster Muncher
86' 944 Turbo - Megasquirt - 326 rwhp/340lbft @ 18 psi
www.edmontonhomelife.com
www.edmontonrealestate.ws
Old 12-14-2004, 11:45 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #8 (permalink)
Administrator
 
Z-man's Avatar
 
Join Date: Feb 2001
Location: NJ, USA
Posts: 8,185
Garage
Quote:
Originally posted by Panzer909
1. It needs topped up with coolant about every 1 1/2 weeks or so with NO external leaks. I even checked the infamous heater valve deep in the engine bay.
Same with my car as the crack developed.
Quote:

2. There's no plume of smoke from the exhaust (other than the fact that its really cold here in PA now).
I didn't have any plume of smoke before the head was replaced either!
Quote:

3. The car drives/idles/accelerates fine and always has.
Ditto.
Quote:

4. The oil looks fine when drained and no real sign of milkshake.
Same with mine, until a certain point, and then the milkshake appeared!

-Z.
__________________
1989 944S2 - June, 2001 - January, 2014

Visit my homepage!
<><
Old 12-14-2004, 12:16 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #9 (permalink)
Administrator
 
Z-man's Avatar
 
Join Date: Feb 2001
Location: NJ, USA
Posts: 8,185
Garage
Quote:
Originally posted by ae1969
How about a compression test and/or leak down and the mystery will be solved.
Nope - that's not going to help diagnose a potential cracked head. I had the following leaddown numbers with a cracked head: 2%, 2%, 3%, and 4%. (Factory spec is 2%, IIRC.) Not bad for a motor with 150,000 miles and a cracked head!!

The problem the compression / leak down test is that they are done when the engine is cold, and the crack is much less evident then. But head up the head (ie magnaflux it) and you'll be able to spot the crack right away.

IF you take the head off, definately Magnaflux it - it will show if it is cracked or not.

Good luck!
-Zoltan.
__________________
1989 944S2 - June, 2001 - January, 2014

Visit my homepage!
<><
Old 12-14-2004, 12:18 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #10 (permalink)
Registered User
 
Join Date: Jun 1999
Location: Vernon, CT
Posts: 849
Pull the plugs and using a strong flashlight, look into the cylinders. If one or more are spotlessly clean, or at least substantially cleaner than the others that's a sign of a coolant leak into the cylinders. The coolant will "steam clean" the affected cylinder, where as the rest will probably have some amount of combustion residue in them.

If you know a mechanic with a borescope, that's a better way of looking into the cylinders
__________________
Mike


'92 968
'01 VW Jetta TDi
Old 12-14-2004, 12:19 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #11 (permalink)
Registered User
 
Eric 951's Avatar
 
Join Date: Aug 2001
Location: Steelers Country
Posts: 2,318
Johnny,

you scared me for a minute--thought you were talking about the "S". good luck in the diagnosis.

Is your clutch still good?

PS--you are invited to my New Years' Eve party at my house--start around 7 PM--bring a friend if you want.
__________________
Eric
86 951-- SOLD!
76 CB 750 Cafe/78 CB 750F/83 VF750F/75 CB750F
69 Chevrolet C-20 Longhorn (family heirloom)
76 F150 Bicentennial Edition/90 FJ62
Old 12-14-2004, 12:21 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #12 (permalink)
 
Now Available for Ordering:   101 Projects For Your BMW 3 Series 1982-2000  [more info]
Mein Gott!
 
Panzer909's Avatar
 
Join Date: Oct 2000
Location: Pittsburgh, PA USA
Posts: 1,520
Garage
Quote:
Originally posted by Eric 951
Johnny,

you scared me for a minute--thought you were talking about the "S". good luck in the diagnosis.

Is your clutch still good?

PS--you are invited to my New Years' Eve party at my house--start around 7 PM--bring a friend if you want.

Well, Eric and fellow board members, I'm afraid that I've got a very heartfelt and tearful confession to make................


I AM talking about the "S"


The problem could be so bad that I'm already in denial! I need a beer - and it isn't even Friday yet. The good news is that the "S" was being pulled from frontline driving duties and is safe & sound in the garage for the time being. I just bought a BMW 325ix for winter driving (yeah!) But at the moment, my budget is nowhere near what is required to R&R a cracked 16v head, so I'll probably have the car just lay low until springtime. Then it will be time to adress the 944$ problem more seriously.


Eric, thanks for the invite - I might just take you up on it! I'll be in touch soon either way.
__________________
Johnny
1987 944S
1984 944 (R.I.P.)
1972 Triumph TR6 - 100% trouble free between breakdowns
2003 BMW 325xi
Old 12-14-2004, 01:03 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #13 (permalink)
Registered User
 
ae1969's Avatar
 
Join Date: Jul 2001
Location: Edmonton, Alberta, Canada
Posts: 4,528
Send a message via ICQ to ae1969
Quote:
Originally posted by Z-man
Nope - that's not going to help diagnose a potential cracked head. I had the following leaddown numbers with a cracked head: 2%, 2%, 3%, and 4%. (Factory spec is 2%, IIRC.) Not bad for a motor with 150,000 miles and a cracked head!!

The problem the compression / leak down test is that they are done when the engine is cold, and the crack is much less evident then. But head up the head (ie magnaflux it) and you'll be able to spot the crack right away.

IF you take the head off, definately Magnaflux it - it will show if it is cracked or not.

Good luck!
-Zoltan.

Uhmmmm I was actually ruling out a bad headgasket etc.............. If your tests come back good on a cold engine you can rule these things out. (99% of the time)

There is no point of considering a cracked head without doing those two tests.

Otherwise its all guess work.

P.S as was mentioned above pull the plugs and take a good look down in the cylinder hole and the actual plugs. If one is getting steam cleaned it will be pretty obvious.

P.S.S diagnosing vehicles is like medicine. Differential diagnosis can always help. Assume everything and rule out those that don't apply........and you are left with what it is.
__________________
Alex - PCA Polar Region - Boxster Muncher
86' 944 Turbo - Megasquirt - 326 rwhp/340lbft @ 18 psi
www.edmontonhomelife.com
www.edmontonrealestate.ws

Last edited by ae1969; 12-14-2004 at 01:24 PM..
Old 12-14-2004, 01:20 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #14 (permalink)
Registered User
 
fast924S's Avatar
 
Join Date: Jun 2003
Location: New Haven, CT
Posts: 3,343
Garage
Send a message via AIM to fast924S
Or you could just Run the car till it heats up and then do a compression and leak down test, theses test should never be done cold, wont be accurate. Also check the plugs to see if any of them look like they are burning coolant. Also you can do a pressure check on the cooling system, Get the tool warm up the car pressurize the system and see if the pressure drops, if it does then you have a bad head gasket
__________________
1986 951, Stock for now.
]87 924S Gaurds red- SOLD after 11 years of ownership
Old 12-14-2004, 01:37 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #15 (permalink)
Registered User
 
Eric 951's Avatar
 
Join Date: Aug 2001
Location: Steelers Country
Posts: 2,318
Quote:
Originally posted by Panzer909
Well, Eric and fellow board members, I'm afraid that I've got a very heartfelt and tearful confession to make................


I AM talking about the "S"


The problem could be so bad that I'm already in denial! I need a beer - and it isn't even Friday yet. The good news is that the "S" was being pulled from frontline driving duties and is safe & sound in the garage for the time being. I just bought a BMW 325ix for winter driving (yeah!) But at the moment, my budget is nowhere near what is required to R&R a cracked 16v head, so I'll probably have the car just lay low until springtime. Then it will be time to adress the 944$ problem more seriously.


Eric, thanks for the invite - I might just take you up on it! I'll be in touch soon either way.
Johnny,

Ouch--sorry to hear I know those S heads are $$$. Although on the bright side--I always liked the 325ix--pretty slick snow machines. Just let me know regarding the party--should be fun.
__________________
Eric
86 951-- SOLD!
76 CB 750 Cafe/78 CB 750F/83 VF750F/75 CB750F
69 Chevrolet C-20 Longhorn (family heirloom)
76 F150 Bicentennial Edition/90 FJ62
Old 12-15-2004, 05:50 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #16 (permalink)
Registered User
 
Join Date: Aug 2003
Posts: 27
Why do you think the head is cracked vs. being warped? I've seen lots of warped heads, especially cars that see the track. Easy to fix on 8V engine, maybe a little more work on 16V. In addition to eating coolant, you might notice tell-tales of water evaporation at the point where the head meets the block.
Old 12-15-2004, 11:22 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #17 (permalink)
Registered User
 
Join Date: Mar 2011
Posts: 2
2001 c4 engine problem

Hey guys, I have the same kind of problem. I am eating coolant as welll. And i dont know where it goes. I took it to porsche and they said there is moisture/coolant in cylinder one. The engine light flashes on startup and stays on after that. There is no oil in the coolant tank, but i think there is coolant in the oil because i drained the oil and it was very thick and black. Any ideas what the problem could be? i was thinking cracked head or blow head gasket. Any pointers would be great... thanks!

2004 c4 tip.
Old 03-28-2011, 12:50 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #18 (permalink)
Registered User
 
Join Date: Mar 2011
Posts: 2
*2001 c4 tip
Old 03-28-2011, 01:03 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #19 (permalink)
Proprietoristicly Refined
 
John_AZ's Avatar
 
Join Date: Jul 2001
Location: ~Carefree Highway~
Posts: 5,419
Quote:
Originally Posted by msalamza View Post
Hey guys, I have the same kind of problem. I am eating coolant as welll. And i dont know where it goes. I took it to porsche and they said there is moisture/coolant in cylinder one. The engine light flashes on startup and stays on after that. There is no oil in the coolant tank, but i think there is coolant in the oil because i drained the oil and it was very thick and black. Any ideas what the problem could be? i was thinking cracked head or blow head gasket.


Any pointers would be great... thanks!


2004 c4 tip.
I enjoy reading old posts-2004! and you actually did search.

I would ask the 911/996 forum members for the best suggestions.

GL
John
__________________
1988 924S 70K 6/2014 ...+ 1987 924S 129K DD
Old 03-28-2011, 05:51 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #20 (permalink)
Old 03-28-2011, 05:51 AM
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 



All times are GMT -8. The time now is 10:25 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.