[adamh]

Ok, recently had my engine warning light come one and it's a misfire on cylinder 3. Car cuts out in the morings until it's warmed up. Was about to start 90k service, so changed all the plugs and cylinder 3 plug show's signs of a misfire. Changed coil packs around and all that, did an engine compression test and all are fine apart from cylinder 3. Has no compression at all. Measured valve clearences and they are all out. Cylinder 1 exhaust has no clearence, so is worse that cylinder 3!

Would I just be looking at a valve adjustment or have a got a more serious problem?
Spoke to a guy at a garage and he was sure it could be a headgasket and that the vlaves rarely wear down, also said the lpg will not make a difference? Even after I told him I have measured the valves and they are all out and done a compression test and cylinder 1 is fine

It's not knocking and still drivable so I can get it to a garage. Just hope a re-build is not on the cards

 

[Woody '04]

are you sure the motor was at the correct position when you checked clearances? it has to be turned after checking each pair or two.

you could very well have burned valves/seats if there was no clearance. i would adjust it to spec and see what happens. was the '03 turbo SOHC or DOHC? DOHC has to have shims changed to adjust and SOHC you just adjust the screw/nut on rocker arm.

absolutely no compression seems to indicate a valve problem. a headgasket problem would likely be causing other very noticeable symptoms and should still have some measurable level of compression even if it was much lower than others. i'm not sure what else would cause this short of doing some extreme modifications and burning a hole in your piston or something. are you sure the spark plug and tester were sealing in the hole?

 

[adamh]

Each time I had the lobes facing away as shown in the service manual. Only mods I have had done is the lpg conversion.
Its DOHC so no screw adjusting

I tested the bad cyinder first and thought it may not be on tight enough so did the rest and went back to it testing it a few times, all with zero compression. Unfortunalty adjusting the valves is a bit out of my reach as I dont feel confident enough taking all the belts off etc. GUess I will have to take it to a garage and see what they say.

Thanks!

 

[Woody '04]

does lpg mean liquid propane gas?! it seems if this was done improperly it could create issues, but if you have some sort of kit meant for the car in reasonably widespread use then you should be OK.

never adjusted valves on DOHC subaru, I'll say that up front. on Toyota DOHC I did before there was a special tool that gripped the camshaft and pushed down on valve cup to allow shim to be removed more easily. Subaru should be able to be done without removing engine, perhaps with a special tool, but I don't know.

 

[adamh]

liquefied petroleum gas, was done a few years back by an lpg specilist. That's never given me any faults. Though I knwo lpg does burn hotter and dryer than petrol so wear is on the increase with the pistons an all that.