95' 850 GLT - BAD CYLINDER TROUBLESHOOT

fredt2 · Post by **fredt2** » 02 May 2025, 17:05

Greetings everyone,
This morning, while i was starting my car to get to work, it felt really shaky, it went away for a while, but as I was coming back home, it came back again, but this time it felt really sluggish too, almost stalling at red lights.
So, after i got home, i started troubleshooting, spark plugs ok, fuel injection ok.
There was some smoke coming out of the dipstick and oil cap, so I'm suspecting a burnt valve or collapsed lifter. I've already removed the cam cover and camshafts, and tomorrow I'm gonna pull the lifters out to check if any have failed completely.

Could this just be really bad lifter, or must it be a burnt valve?

Post by **scot850** » 02 May 2025, 19:21

Hard to tell now. I would have suggested having someone sitting in the car and removing the spark plugs one at a time to see which cylinder made no difference to the running.

Another option was to test the cylinder compressions to see if one was lower than the others. Then if you have one lower than the others, add a tea spoon of oil into that cylinder and see if the compression improved. If it improved then the piston/rings are bad, if no difference you either have a bad lifter or burnt valve.

Having disassembled as far as you have gone, it will be a case of taking the head off and seeing if any of the valves is bad. You could have tried a small camera on a wire (boroscope) which can be added to a cell phone and if you get one with additional prism lens allowing looking backward/upwards, you may have been able to see a bad valve without first stripping the engine.

Neil.

Vova585 · Post by **Vova585** » 02 May 2025, 21:44

1. Perform compression test. (Remove fuel pump relay). If significant difference between neighboring cylinders proceed to leak down test(otc tool is great, but HF option is cheaper and will work for a couple times). If still suspect bad cylinder head valve-borescope eval through the spark plug to visualize the valve.
However, I would suspect some codes with this poor performance. 95 is a split year between obd 1 and obd 2? I think some cars might have both? Let's read the codes first and keep the engine together for now. Have you checked fuel pressure during idle and acceleration?

fredt2 · Post by **fredt2** » 03 May 2025, 16:28

Update as of now:
got myself a cheap boroscopic camera, put it into all the cylinders, and lo and behold, a chipped valve, pic below.
Now i'm going to take off the head and order the parts. Also, all of the lifter except for one, which is collapsing a bit, but not enough to f a valve up.

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