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Discussion Starter #1
Since the end of last week my gl has been making a ticky/chuffy noise and running a bit ropily.

I thought i was chasing a leaky exhaust manifold/exhaust joint and on sunday i welded up a crack in the downpipe (no difference) and monday i took off and refitted the exhaust manifolds (with no difference).

Drove it to work today and it got worse and worse until it felt like it was running on 3 cylinders. (though i have been getting 25+mpg which is good!) It would still tick over once warm and go 60mph though!

Took the plugs out and did a compression test tonight and it is running on 3 cylinders - pot 1 has zero compression and the other 3 are at 150psi+.

There is a spark there (have run it with the plug resting on the engine), but
pulling the lead off cylinder 1 while it is lumpily ticking over makes no difference to its running but any other lead makes it stall.

It is making what sounds like an exhaust leaky noise while running. Like a kind of ticking/chuffing noise.
Cant feel any drafts anywhere but there must be one!

Its not using any vast amounts of water (i have a leaky pipe so it is using a bit), the oil is fine and it doesnt seem to be pressurising the engine (no clouds coming out of the filler cap or new leaks anywhere)

What do people reckon.

My choices would seem to be:

head gasket gone to atmosphere or the timing chain area
valve broken (though i havent noticed it passing the bits through)
valve spring broken so a valve is stuck open (so the noise i can hear is it blowing back into the inlet or something?)

place your bets! :lol:

where can i buy a gl downpipe and manifold-downpipe gaskets from?
 

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Exhaust valve's got to be a good bet.........

Bit unlucky, Tom - you haven't been spanking it that hard, have you?

Chris.
 

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Tom's GL wishes it was a two-stroke :lol:

I reckon broken spring, at least if it is that is should be the easiest to replace. Is it possible to replace a valve spring without removing the head or will that result in the valve dropping into the bore?

If not sounds like the head has to come apart either way!:(


If it makes you feel any better my GL has started ignoring the fact that I "fixed" the WUR and is mis-behaving again, I'm sure there are reasons why I haven't bought a new car yet, just sometimes the GL's foibles make them hard to remember!:p
 

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Busted valve gets my vote too. Sounds very similar to when a lump of valve fell off one of my allegro engines :)
Try a motor factor for a downpipe, one of the ones near me had a centre pipe which none of the tyre/exhaust places could supply.
 

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Discussion Starter #5
VikingSpirit said:
Tom's GL wishes it was a two-stroke :lol:

I reckon broken spring, at least if it is that is should be the easiest to replace. Is it possible to replace a valve spring without removing the head or will that result in the valve dropping into the bore?

If not sounds like the head has to come apart either way!:(
I think that you can pressurise the cylinder with an airline to keep the valve up, but it sounds a bit tricky and im not sure i could get a good enough seal without a decently machined connector to go in the spark plug hole.
 

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Discussion Starter #6
Penguin45 said:
Exhaust valve's got to be a good bet.........

Bit unlucky, Tom - you haven't been spanking it that hard, have you?

Chris.
No, I hadnt really been spanking it that much atall!

nutcase said:
Busted valve gets my vote too. Sounds very similar to when a lump of valve fell off one of my allegro engines :)
Try a motor factor for a downpipe, one of the ones near me had a centre pipe which none of the tyre/exhaust places could supply.

Ive never broken a valve before. How do they usually go?

am i likely to have lost a chunk off it? and if so is this likely to have evacuated without knackering my piston and head too much?
or is it more normal for them to crack? which i assume would be enough to totally kill my compression?
 

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Tomarse said:
I think that you can pressurise the cylinder with an airline to keep the valve up, but it sounds a bit tricky and im not sure i could get a good enough seal without a decently machined connector to go in the spark plug hole.
It sounds like a valve is the culprit, could be a headgasket but it would have to miss all of the waterways.
I have a snap-on cylinder leak down tester and the airline adapters to fit into the spark plug holes if you need to keep the valves up if a spring has failed, but i think you will be taking the head off.
 

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I think I've had 2 let go - one burnt out across an edge, so small bits meant no additional damage. The other cracked and a big lump fell off. That caused some piston crown damage.
 

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Not been running too lean on LPG have you? If so, I'll say holed piston, not because I think it is really likely to be that, but because I like to play Doommonger and also 'cos nobody else has suggested that yet!! ;)

Seriously, hope its an easy fix Tom...
 

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Discussion Starter #10
Mark_A said:
Not been running too lean on LPG have you? If so, I'll say holed piston, not because I think it is really likely to be that, but because I like to play Doommonger and also 'cos nobody else has suggested that yet!! ;)

Seriously, hope its an easy fix Tom...
It has been running almost perfectly (ive got a wideband lambda on it).

sticho->very slightly lean when crusing. Lean on the overrun (my 99T also does this) and going very slightly rich when you put your foot down.

If the piston had gone i'd expect loads of vapour coming out of the oil filler and for every single gasket and oil seal to be leaking - when i got my series 2 it had knackered piston rings and used to breath heavily and leak from every available joint!
 

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Discussion Starter #11
apologies for rubbish phone piccys.

Only a little bit or damage but its obviously enough!

This is the exhaust valve from cylinder 1.



 

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Discussion Starter #14
no damage to the seat or piston or head or anything! :)

I wonder if this has anything do do with the last 25k of lpg running or if is just down to it being 170k miles and 27 years old?

I wonder if it has been damaged for a while and just recently got really bad. I had slightly lower compression on that pot before i did the head gasket the other month.
You couldnt see the damage until you looked closely - the face of the valve is fine.

are the valves from a 99T different to a GL? (i cant recall if they all got the same ones or not) I've got a spare T head and am trying to decide if i should swap the whole set over..
 

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Discussion Starter #16
VikingSpirit said:
Only thing I can thing of is possibly the cam is different and the exhaust valves on a turbo are supposedly sodium filled aren't they? I doubt it would matter on a GL though. You could always swap bits over.
yeah. i know the cam is different. not going to use the whole spare head, just the valves.

i cant remember if they are all sodium filled or just the turbo ones.
 

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Discussion Starter #17
my gl has

83 62 29 - which appear to be normal.

the turbo has

93 07 35 - which have a warning about disposal of sodium filled valves in the EPC - so im assuming are the sodium ones.
 

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Tomarse said:
my gl has

83 62 29 - which appear to be normal.

the turbo has

93 07 35 - which have a warning about disposal of sodium filled valves in the EPC - so im assuming are the sodium ones.
At least the damage isn't too bad, It easy to sort out a replacement valve.
From 77 onwards Saab used sodium filled valves on fuel injected engines.
 

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Discussion Starter #20
I am fitting the set of sodium ones.

Am just setting the valve clearances now - have measured, assembled, feelered and gone through my box of shims to find some that should do the job. Now i have to take it apart again to fit them. I hate this job!
Inlets are perfect and dont need touching but all the new valves need smaller shims fitting to up the clearances.

The haynes manual i am using today has 2 sets of numbers for the clearances too - some 'setting' figures and 'checking' figures. The setting ones are tighter. Im not sure why they should be different though!
 
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