Compression failure.

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Compression failure.

Morty Mort

NobodyBlamesTheHappyGuy!
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Hei.

The story:

Was driving around town with nicely warm engine (90 degrees). Stopped and picked up my girlfriend - we were chatting outside the car while it idled. Then it stopped and never started again.

The engine jumped back and forth and backfired through the SPi-module. The engine is the 1108 cc and is sitting in an Uno from 1993. It never started when cold either.

I suspected the ignition / vacuum advance and got a scrapyard spare. No progression. The vacuum on my last distributor was not working, but the engine ran anyway.

So today:

I bought a compression tester to check each cylinder. I refer to cylinder 1 as the leftmost when looking down into the engine bay (is that correct?). Well - tested for spark against top, and it was fine. Backfire through intake and no start. Compression shows 12 bar.

Next cylinder. Same procedure. Compression shows 9,5-10 bar. A little lesser.

Next cylinder - number 3 from left. There is a spark here as well, but with the plug removed the engine starts [:0][:0][:0]. It's running smoothly on 3 cylinders, not jumping like hell as when it stopped earlier. No backfire.

The 4th cylinder is a copy of the 3rd. The same happens. Runs fine on 3 cylinders. What's interresting is that these two cylinders show the same compression: 8, but it falls slowly to 4 when the engine idles (still in 3 cylinders).

So - I packed all plugs in and started. B) NOT. Backfire and not a start at all.

Are these two cylinders sharing the pressure?
Why backfire when one of the plugs on cylinder 3 or 4 are out?

Is it the HEADGASKET? [xx(] Between two cylinders[?]

There is no milkshake in the oil filler, the camshaft and vents look fine. No water loss. No oil in water. New plugs, HT leads, oil, etc. one month ago before the MOT.

I'M IN THE DARK HERE! Please help ;)

Morten.


gas lowered on abarth wheels. upgraded interior and visuals. audio through phoenix gold and BLOWN kenwood.

projects: air in and out.

Honey that ain't no pistol - that's my LOVE GUN.
 
head gasket from 3rd to 4th has gone by the sounds. you won't get water in the oil or anything like that if the head gasket only fails between two cylinders

cinq_small.jpg
 
Well, I don't know if I'm lucky or not. My woman and our son have travelled by plane to her home-town in northern Norway. I'm to follow in 12 days - by car. It's a 1000 km trip each way. Yes 1000 km. I'm happy the gasket blew (if it is the gasket) before I was in the norwegian wilderness left alone without mobile phone coverage.

Do you think the head needs skimming? I don't know exactly what "skimming" is but I suppose it's to make it completely flat by grinding etc. I know it's aluminium so it expands more than cast iron. (I've seen some tires frozen to the ice and the alloy just spinning inside the tyre. This doesn't happen on iron wheels.)

Have to go to Fiat on monday to order a gasket then... Do I need any other gaskets? The exhaust? The air/fuel intake? Etc.? Is there a package?

Morten.


gas lowered on abarth wheels. upgraded interior and visuals. audio through phoenix gold and BLOWN kenwood.

projects: air in and out.

Honey that ain't no pistol - that's my LOVE GUN.
 
Yu could get a full head set from a parts house.

That has enough of and the correct seals to renew every seal in the head.

Tom (AofB)

95 Cinq Sporting - Rattly GrpN Catback Exhaust, <font color="black">Buckets</font id="black"> and 3pt Harnesses,Sexy VW styleé dials (that look great, but dont work!! :)D)), 10" Sub and 6x9's, ETech Wing. Lots of Dirt!
1242cc Engine in car, not starting, boot delock soon, K+N still in garage!
 
i think the gasket set costs around £30. You are better off skimming the head as well, just to make sure its right.

it might not be that head gasket tho, il happily admit i don't know all there is to know about cars!

cinq_small.jpg
 
Ok. Big thanks to all. Then it's the head gasket.

How easy is it to tell if it needs skimming? Will it be obvious with warps and knurls, or is it almost invisible to the eye?

I am actually looking forward to doing this. Firstly (can I write that???) I feel sorry for the car, and secondly it feels like a challenge.

Morten.


gas lowered on abarth wheels. upgraded interior and visuals. audio through phoenix gold and BLOWN kenwood.

projects: air in and out.

Honey that ain't no pistol - that's my LOVE GUN.
 
Well.

Managed finally to remove the head. The gasket seemed fine. Until I ruined it when removing the cylinder head. The head was removed with both intake and outlet manifolds and cam. The head has no damage from a blown gasket or any cracks. A lot of carbon though, propably due to many non-starts lately.

The cam rotates nicely and opens and closes all valves. How should they look? The inlet valves have a little groove in them, just like a flat finger on non-burnt clay. The inlets are 2,4,5,7 counted from the timing belt.

What can be wrong then?

What's strange is that it concerns two cylinders. If I remove the HT lead from cylinder 3 or 4 counted from timing belt it starts fine (running on 3 cylinders). If I remove the HT lead from spark plug 1 or 2 the engine stalls and backfires until it chokes itself.

I just don't get it!

Suggestions anyone?

Morten.


gas lowered on abarth wheels. upgraded interior and visuals. audio through phoenix gold and BLOWN kenwood.

projects: air in and out.

Honey that ain't no pistol - that's my LOVE GUN.
 
Take it the block and head mating surfaces are fine and nice?

Checked for head warping?

If its not that, it could be something really horrible, like the piston rings having died. Is yure car quite high mileage?

Thats the only thing I could see that could lead to no compression if its not the head!

Tom (AofB)

95 Cinq Sporting - Rattly GrpN Catback Exhaust, <font color="black">Buckets</font id="black"> and 3pt Harnesses,Sexy VW styleé dials (that look great, but dont work!! :)D)), 10" Sub and 6x9's, ETech Wing. Lots of Dirt!
1242cc Engine in car, not starting, boot delock soon, K+N still in garage!
 
Both surfaces are completely flat and with no damage. The engine has run 120.000 km. Someone want to calculate? 60 miles is about 100 km. 120.000/1,667 = 72.000 miles. Not very much is it?

Bloody hell. I have no idea what to do!

Morten.


gas lowered on abarth wheels. upgraded interior and visuals. audio through phoenix gold and BLOWN kenwood.

projects: air in and out.

Honey that ain't no pistol - that's my LOVE GUN.

THE UNO IS STILL DEAD!
 
hmm..both mine were fine at that mileage.

Could well be piston rings!..not great. might be an idea to wait for a response from a fountain of knowledge!

Tom (AofB)

95 Cinq Sporting - Rattly GrpN Catback Exhaust, <font color="black">Buckets</font id="black"> and 3pt Harnesses,Sexy VW styleé dials (that look great, but dont work!! :)D)), 10" Sub and 6x9's, ETech Wing. Lots of Dirt!
1242cc Engine in car, not starting, boot delock soon, K+N still in garage!
 
Yeah. Repair manual say its an engine out of car job. I reckon it could be done with it in the car, but with great difficulty!

Tom (AofB)

95 Cinq Sporting - Rattly GrpN Catback Exhaust, <font color="black">Buckets</font id="black"> and 3pt Harnesses,Sexy VW styleé dials (that look great, but dont work!! :)D)), 10" Sub and 6x9's, ETech Wing. Lots of Dirt!
1242cc Engine in car, not starting, boot delock soon, K+N still in garage!
 
I think the engine might still be in the car. Remove the sump pan, disconnect piston rod "thing" and push it up the bore. Eyh... I've learnt quite many cool engine words since I joined the forum. :)

It still doesn't explain how two pistons should fail immediately, and one work when the other is "unsparked". I'll sleep on the problem.

Thanks for answers folks. Good night to you all.

Morten.


gas lowered on abarth wheels. upgraded interior and visuals. audio through phoenix gold and BLOWN kenwood.

projects: air in and out.

Honey that ain't no pistol - that's my LOVE GUN.

THE UNO IS STILL DEAD!
 
Don´t know about the two piston problem. Is the engine sparking right? Like do they go in the right firing order, maybe reversed plug wires could cause that unspaked 3 cylinder starup but wouldn´t explain loss of compression. Need more info to help like cylinder bore condition etc.
 
Morten,

I still think it's a problem of stuff leaking from one cylinder to another, the equally low compression readings do support this. Are you sure the gasket was intact - no markings, suggesting leaks etc?

BTW, shot piston rings wouldn't make the coolant bubble. The reason behind it running with one spark plug disconnected could be that the gases are being blown into the next cylinder and preventing a proper ignition on the next cycle.

Pete.

Links: 1242cc cinq, turbo cinq, Cinqs&Seis Yahoo group, Clubcento
 
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