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Discussion Starter #1
Hello everyone.
I'm new to the forum as i've just rejoined the Saab community.
I recently picked up a 93 900s (non-turbo) convertible with a ton of mileage on it.
I test drove fine and didnt show problems

I changed the oil in engine and manual trans and gave everything a good inspection.
After daily driving it for a little over a week
It was using coolant. Checked the plugs and saw no sign of 'clean' or 'wet' plugs so was hoping headgasket was ok.
I replaced 1 suspect bypass hose and what appeared to be a leaking radiator cap. Afterward i found a spraying hoseclamp cut in the 'T' shapped bypass hose on the water pump and badly balloned upper radiator hoses.
I decided I'd replace all the hoses and flush the system.
After that very long and difficult service i just got it back on the road today.

Here's my problem:
Intermittant rough idle and bad miss. Thought it was AIC related, but while fiddling with everything and bleading the coolant, it started spewing white mist out the exhaust.

Headgasket....

Pulled #1 plug and it was soaked. Cylinder is visibly wet. All other cyliners look fine.

#1 compression tested strong at 220psi. Shouldnt it be lower with a bad HG?
#2 was 205psi
#3 was 190psi
#4 was 205psi

Here's the strange thing. Exhaust mist seems intermittant as does the miss and rough idle. Also, it was showing no signs of HG problems before the flush. (Other than loosing coolant of course, but i did have serious hose problems)

Is it normal to have good compression on a bad headgasket?

Is there any chance re-torquing the head might fix this? (Long shot...)

Where does one get the 'best' head gasket these days? I definitely want the latest revision etc...

Thanks in advance for the sorely needed advice! I love this little car and am thrilled to have a Saab again. I wish i still had my 99!!!!!
 

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If no 1 plug is wet it's obvious water is getting in past the head gasket. The leak may be marginal and the higher pressure due to partial hydraulic locking. Look for tell-tale bubbles in the water reservoir when the engine is running. There should be none and the exhaust steam is a giveaway.

Torquing the head bolts more should not be attempted. The Saab head bolts are stretch bolts and torquing more will almost certainly have no effect.

If you want a quick fix and the leak is small, you may get a semi-permanent fix by using Steel-Seal. https://www.steelseal.com/

If you do source a new head gasket, ensure it is an Elring one. Elring are OEM. http://www.elringparts.co.uk/products/elring/
 

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Discussion Starter #3
Yeah, definitely bubbles in the overflow tank. I wasn't going to up the torque, i was considering backing off and re-torquing... Long shot, i know... But the good compression was confusing me. It appears thats fairly common though...

So it seems USA members have luck ordering from eeuroparts?

This thing has 248,000 miles on it. A lot has been done, but i dont know what.

I have a good shop to check my head and NOT grind the valves! (Thank you forum! I wouldnt have known that one!!!)

What else should I consider while in there?

I need to check timing chain tensioner but it has a wierd 'ting' that i cant track down. I thought a noisy chain would sound more like a rattle??? This sounds more like tapping a nail on sheet metal...
I'm going to assume it needs a chain and guides...

Crank position sensor? (How difficult is it?)
Main seals F & R?
Oil pump o-ring?
Distributor o-ring?
Other assorted 'while you're in there's"?

Thanks for the quick response!!!
 

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Discussion Starter #5
Wait a minute. So I reset the tensioner, reinstalled it snug, and took it back out to check it?

10.65 mm
Is this a valid check or does the engine need to be run before rechecking? Maybe I bumped it on the first check? Maybe the timing chain is good?
 

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Wait a minute. So I reset the tensioner, reinstalled it snug, and took it back out to check it?

10.65 mm
Is this a valid check or does the engine need to be run before rechecking? Maybe I bumped it on the first check? Maybe the timing chain is good?

It will not extend fully until you have turned the engine over since you will not have all the slack on the back side of the chain until then.
 

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Discussion Starter #8
UPDATE:

Block is pitted. Looks like someone had JB weld in it before but I dug it out. I couldn't tell what was what with all the gunk on the block deck so it came out if that is indeed what it was.

The head is pitted... Pretty badly. Someone has been in here before and made a mess of the head surface. Gouged and rough. It'll need skimmed I think.

However, that will not fix the pitting. So my options are:
-Another head: unlikely as pickings are slim around here

-weld the head: this is an option to explore, but I'll have to find someone good as I don't know anyone right now. Also, no idea on what it'll cost



-mill the head and use a shim: does anyone have a source for a shim? My engine guy is checking Monday but I thought I'd ask in here to see if anyone know of any and has experience with using them???
 

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Just plane the head. The half-moon head thickness guide at the bottom of the last pic shows you have plenty of head dimension to play with. If you have very deep pits, fill them with JB weld before planing, which is the Saab approved way of dealing with them.

PS - The half-moon shapes at the side of the head, gasket side, correspond to 40 thou" (0.040"or 1mm) off the head thickness, which is the Saab recommended max planing allowed. You can measure the thickness left by measuring the half-moon depth from the head gasket face. If it's 40 thou"/ 1mm the head will not have been planed at all.
 

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Just plane the head. The half-moon head thickness guide at the bottom of the last pic shows you have plenty of head dimension to play with. If you have very deep pits, fill them with JB weld before planing, which is the Saab approved way of dealing with them.

PS - The half-moon shapes at the side of the head, gasket side, correspond to 40 thou" (0.040"or 1mm) off the head thickness, which is the Saab recommended max planing allowed. You can measure the thickness left by measuring the half-moon depth from the head gasket face. If it's 40 thou"/ 1mm the head will not have been planed at all.
if there are bad pits in the head(I did have some in one of mine), the place that skims the head, should be able to aluminium weld it like they did mine, and then skim it.
 

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Discussion Starter #14
Just plane the head. The half-moon head thickness guide at the bottom of the last pic shows you have plenty of head dimension to play with. If you have very deep pits, fill them with JB weld before planing, which is the Saab approved way of dealing with them.

PS - The half-moon shapes at the side of the head, gasket side, correspond to 40 thou" (0.040"or 1mm) off the head thickness, which is the Saab recommended max planing allowed. You can measure the thickness left by measuring the half-moon depth from the head gasket face. If it's 40 thou"/ 1mm the head will not have been planed at all.
Everything I'm reading says the head can only be cut .4 mm (.0016 in)
Are you saying you don't agree? I think it's mainly due to cam timing and timing chain slack?

I measured my head w/ calipers today and it's 140.48 mm so I'm pretty sure it's never ben milled. That's good anyway...

I'm considering the epoxy for the head, but there seems to be argument that it doesn't work as well for aluminum since it stretches more with heat cycle. IDK...
Welding it may be better? IDK
 

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The 'half-moon' cutout is the indicator. SAAB Service Bulletins endorse the epoxy fix. There are no timing issues.
I do know, but you should do what you think best.
 

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Welding can cause damage to the head, even when done expertly.:nono; Follow Guru Jim's advice.
I'm considering the epoxy for the head, but there seems to be argument that it doesn't work as well for aluminum since it stretches more with heat cycle. IDK
Stop trying to imagine problems that don't exist. The epoxy is not going anywhere. It's trapped under great pressure by the gasket and is the Saab approved method.
 

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Discussion Starter #17
OK, after annoying you guys before, I wanted to give an update.
First, I consider myself a competent mechanic and craftsman. I've done a lot of work on vehicles and have rebuilt a couple Landcruisers including complete engine rebuilds. I'm well familiar with head gasket issues on my 87 supra turbo and 93 Landcruiser, but this erosion/pitting problem is new to me. I'm also very new to Saab 'mechanics' so I'm trying to get up to speed. Every car brand has its quirks and learning from those who have been there is my preferred method of learning.
So! Thank you for the assistance, and I'm sorry if I annoyed anyone with my fact finding on milling and epoxy.

I decided to both fill with JB weld hi-temp and skim the head. The surface was not warped, but was pretty chewed up and gouged from previous work. I soda blasted first, epoxied, then sent it for the skim.
I'm very happy with the results!
 

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Discussion Starter #18
I feel dumb making a separate post for each picture, but I can't seem to attach multiple pictures to one post on my iPad (although I could in my first posts. Strange)

Close up of epoxy leavings:
 

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Discussion Starter #19
Plenty of room left on the 1/2 moon 'indicators'

My engine guy said the valve seats and guides looked ok. He replaced the seals for me and told me it was a pita... I'm glad I had him do them!

I also epoxied and hand filed the horrible pitting on the coolant hose fittings on the head and thermostat housing. They came out good! Hope they hold as well...

I've cleaned and epoxied the block deck, and am re-assembling this weekend.

I have a new H2O pump going in and all the hoses are new. New Benz & distilled coolant and new oil. New 82c T-stat and fan switch. AC Fan mod done (it wasn't done on this car)
Hopefully this should extend the life of this head gasket!?!

It appears that many of the coolant passages in the head/block are similar to to common fail point? This makes me wonder the cause. Is it heat related? Maybe it's hotter back by the firewall with the cast iron exhaust right there? Maybe something about the coolant flow in that area doesn't cool as well?

This thinking has me planning on using exhaust wrap on the exhaust manifold to try to move that heat out of the firewall area. Any thoughts on this? Has anyone attempted this? Results?

Thanks again for all the assistance!
 

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