Hello everyone and hope you're doing well in these unusual times.

I'm new to this forum and of course a new X-Type owner.
I bought for cheap a 2003 x-type auto LPG to own and play with a great sounding n/a V6 once until they're gone forever. They seem to be phased out rapidly for at least 10 years now.
I knew it had many problems mechanically and exterior body is in bad shape. The inside on the otherside is in superbly good condition.

The biggest problem it has is that there is almost no compression on cylinder #1 (Bank1 first one near the timing chain or closest to the driver in a RHD car).

What I've done and what I know so far:
- while the engine is running I cut the gas on cyl #1 and observed no change in engine regime; while cutting the fuel on each of the other 5 cyls I could see a engine change on all of them; they run ok or at least firing ok. that's how I started thinking about compression.
- I've tested the compression on cold with a cheap compression tester and I'm getting arround 9 bar (120-130psi) on 5 of the 6 cyl (#2 to #6); I know it's a bit low but at least they're relatively constant and I'm not very sure the tester is very accurate;
- the pressure on the cyl #1 was around 1 bar (20psi) on dry and around 3 bar (40 psi) with some oil poured in the cylinder to improve piston ring sealing to the wall.
- cylinder #1 had a bad ignition coil that din't trigger any spark when checked; I've changed it with a new coil;
- I've changed the sparks with Denso regular; the original sparks were Denso Iridium in good shape but pretty old; the spark on cyl #1 was black and wet and the other 5 were pretty clean with "as expected" color and normal carbon buildup.
- there is no contamination in oil or coolant and the level of both remains constant.
- there are no air bubbles in the coolant while the engine is running.
- trying to "unseize" the piston rings, with the spark plug removed, I poured some petroleum based dilutant into the intake port and with the intake valves closed (not 100% sure but visually they seemed closed), all the dilutant poured imediately in the cylinder chamber as there were no valves; seems that intake valves don't seal anymore.
- after completely fulfilling the piston, I've observed the dilutant level decreasing relatively fast (aprox 100 ml/min) until the level dropped below the exhaust valves; below the exhaust valves level, the dilutant remained in the cylinder much longer (probably 1 hour) until it all passed the piston rings down in to the engine oil. I know that some dilutant reached the oil because I smelled the oil and it smelled like dilutant. I know I must not run the engine with the contaminated oil but I ran it 2 minutes for a quick test. I have the new oil but wait for a resolution on the engine.
- with engine running the exhaust gallery at the rear of the engine sounds louder than the gallery at the front without having any holes in it.
- OBD scanning reveals only 2 codes related to the engine, one bank 2 upstream O2 sensor and one downstream bank 1 O2 sensor related to their pre heater circuit malfunctioning.
- there is no abnormal oil or coolant consumption nor any smoke on the tailpipe.

My questions are the following from the simpler to the more complex resolutions:
- is it possible that the exhaust valves clogged so badly with unburnt fuel (because of the bad ignition coil) that they don't seal at all?
- is it possible to perform some static valve cleaning with some "magic solution"
- is it possible to investigate the state of the valves just by removing the head cover without taking the cyl head of?
- is it possible to take the rear cyl head off without removing the engine from the car?

It's a lenghty post for a small gap leading to a big problem.
Thanks in advance guys.
Any sugestions are welcome and hapily, I'm not pressed to decide quickly what to do with the car.

 

Iulian,

Your post was automatically locked for moderation. I can't see a problem with the content and have unlocked it.

I've also removed the duplicate posting.

Graham

 

Welcome to the forum.

If you take the valve covers off you might be able to see the top of the valve stem and see if it is at least moving when you rotate the cam. If it is not maybe it is bent? Or the spring is broken? Maybe this is not very useful because you can't do anything to fix the valves until you take the head off. Sorry I can't answer more, I have never taken the heads off.

I would not run the car like this for very long as the unburned fuel from the cylinder with no compression will damage the catalytic converter.

 

Thanks for unlocking.

I'll come with some details that didn't make it to the original post:
- The car has at least 240k km and the odometer doesn't work for a while.
- I don't know how long the car ran on 5 cyl but it could be 3-5k km based on official technical inspection (MOT) mandatory once a year.
- OBD scanning reveals only 2 codes related to the engine P0037, P1647 , bank 2 upstream O2 sensor and one downstream bank 1 O2 sensor related to their pre heater circuit malfunctioning. These are not a prioroty right now.

 

Thanks for the reply DH.

I'm not running the car like this. I only run the engine for 5 minutes to test it after some investigations or workarounds. The Citroen is my daily driver. Altough in these time of isolation and social distancing is more like a weekly driver.
I will prepare the engine head cover for removal and do some investigations on top of the valves and see if anything unusual pops-up.

Any other sugestions are still expected.
Even striking answers as "remove the engine and replace the head" are welcome

 

You could try buying an endoscope to poke into the spark plug hole. The devices that connect to your smartphone are not that expensive.

 

My questions are the following from the simpler to the more complex resolutions:
- is it possible that the exhaust valves clogged so badly with unburnt fuel (because of the bad ignition coil) that they don't seal at all?
As you run on LPG, exhaust valve is probably burned, and leaking. common problem on LPG cars.
- is it possible to perform some static valve cleaning with some "magic solution"
With such low compression on other cylinders, not worth it.
- is it possible to investigate the state of the valves just by removing the head cover without taking the cyl head of?
Worth a try, maybe your lucky and only have broken valve spring...
- is it possible to take the rear cyl head off without removing the engine from the car?
No, but removing the engine is not big job as it sounds. And in your case replacing with good used engine or rebuilding yours is cheapest option on the long run.

 

Hello and thanks for the replies.

I just bought an endoscope camera and I'inspected the cylinder. And there are good news and bad news.

The good news is that intake valves are perfectly fine. I've said in the first post that the intake valves are not sealing but I did the test wrong without the valves completely shut. Now I did the intake test again with the valves completely closed and they are sealing perfectly.

The bad news is that I've inspected the exhaust valves and one valve is definetly not sealing ok. I have some imaging but the quality of the camera is very very low. Nonetheless it allowed me to see the failed valve.
One of the exhaust valves has the head contact area (sealing) as a complete and uniform line as long as I could see it.
The other exhaust valve has the contact as a nonuniform and intrerupted sealing area wich means that the valve is either burn or it has deposits on it. I've attached a video to this post.

@luka000 I know that the car runs on LPG but the other cylinders seem to be fine, so I think that LPG is not the main cause of this issue, especially considering that it seems that only one valve is visibly damaged. Remember that I think the car ran for a while with a bad ignition coil.
My other car, the Citroen C5, is also on LPG but it has a more advanced Prins system (twice as expensive as the entire JAG ) with a valve additive dosing system built into the injectors meant to take care of the intake valve and drop the cylinder temperature as well, reducing the risk of exhaust valve damage. This additive along with the additive feeding system, theoretically allows LPG installation on every engine even those that forbids it explicitly. That's what the guy that installed my LPG system told me (he ran the system on 2 Hondas that are notoriously non LPG friendly).

Anyway, what would be a normal compression for this engine? I fugitively scanned the JTIS but couldn't find it at first run.

By looking at the video to this post is there anything I could do to fix the cylinder presure without taking the engine off the care/head off the engine? I'm still hanging on this possibility.

Thanks.