I have a 1990 Volvo 240 sedan non turbo that has really high cylinder compression readings. #1,2 and 3 = 195psi and #4= 200 psi.

These seem like very high psi reading so I am thinking that maybe my cat converter is plugged up maybe?

Anyone have ideas or comments?

Thanks for responding.

My German market 1991 240 sedan is 195#, all cylinders, cold engine, throttle wide open, and all four sparkplugs out with fully charged battery. 160k miles.

My 1992 240 North American market is 175# in all four cylinder, same test config, Could use a valve adjust re-shim. 180k miles.

My 1990 240 wagon varies around 175-180 and the #2 or #3 is 140, was a stuck ring, I guess, same conditions yet engine was a bit warm. 200k+? Unsure.

If indeed compression was excessively, you'd get pronounced valve ping.

Your ZIP code indicates CA-state. So, if yes, your 1990 240 must operate within emissions requirements.

Why, what are the symptoms you are encountering? CHECK ENGINE light is on?
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I’m in Fairbanks Alaska. No bad symptoms I just purchased the car and completed a compression test to know more about the car beforehand. The high compression l did not bother me to much since I did buy the car.

There are no check engine lights on and it actually runs really smooth. I am just being cautious as I am becoming more familiar with this 240 sedan. The only real problem area that need immediately are a loud exhaust needs attention, replacing the heater core valve and giving the sedan a good detailing job inside and out.

Kevin T.

I'll hazard a guess that the compression is normal.

Is it originally Canadian market, maybe? You have injection yes?

You've verified a clear PCV system that breathes freely, also?

Check the flap valve in the air filter box. They get stuck to hot only air. Replace the air temp thermostat or remove the silver accordion hose or block the lower, inner hot air inlet after you ensure freely breathing into the air filter box. As you are in Alaska, maybe keep the aif filter box preheather control working by replacing the thermostat. Calorstat is OEM? iPd has em.

You can call the dealership, or other ways to check, whether the engine is original to your 1990 240.
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Have you driven the car? I think that clogged cat would cause problems at high engine speed.

James, thank you for taken time to respond. I have driven the car and it runs great at 60 - 65 mph and at lower speeds also. No hesitations in the engine.

AKKevinT

What Volvodad wrote - or another possiblity but highly unlikely would be a worn out camshaft. Compression readings of 190-200 are not uncommon. Years ago I worked on a 140 showing 230 in a compression test. Those motors did wear camshafts and that was the cause in that case.
High readings would have nothing to do with a cat. - Dave

VolvoDad and Heck,

Thanks for sharing your experiences and responses. It helps to know that other folks out there have compression readings and their Swedish torpedo’s survived.

I think I will disconnect the exhaust system from the down pipe and perform another compression test and compare the readings. I will post my readings here after I get that done.

Thanks again for taking time to share your knowledge. Much appreciated!

AKKevinT

Don't waste your time. Disconnecting the exhaust wont make a bit of difference.
You could buy or borrow a "scope" (I don't recall the correct name). With that you could remove spark plugs and take a look inside each cylinder - looking for carbon buildup in the piston tops and valves. I think if the cam was off a tooth one way or the other could effect compression - but I'd think that would effect running in a big way.
Does your motor use any oil? I would maybe do a cold vs hot test. -- Dave

Heck,

Good idea. I will try the cold test since my first test was hot test.

AKKevinT

Hi,

Personally, I think that the engine will be turning over to slow, during the test, to push enough air into that big of pipe and get any sort high of back pressure to cause high readings.
If it where the case it would have to be capped!
High readings could be the camshaft but only on the exhaust valves since it is getting air in.
But why only the exhaust valves is my question then?
Cam “Lift” on both are about the same distance and the exhaust valves are bigger to allow for the expanded gases to flow out.

A plugged exhaust pipe will cause lack of power especially during acceleration.

What are the symptoms that you are having to warrant the compression test to begin with?

Phil

Hi Phil
The sedan is a recent purchase so before making an offer I completed a compression test to
give me more information about the sedan. It has 140K on the odometer and the body and interior are in cream puff condition for an Alaskan based Volvo. So I believe the mileage is pretty accurate. The car really sounds good and runs fine.

Since the readings on compression were consistent I felt it could be a reasonable third car The only repair issues or concerns include rewiring the electric window wires in the door boot with arctic grade wire, installing a new heater control value, and a loud exhaust system (which I have not yet diagnosed why it is loud). Every thing else seems good to go.

One other mild concern was the block has a fair amount of gunk around the valve cover but no dripping or ozing fluids anywhere. Thought that might be related to higher compression readings.

Since there no certified Volvo mechanics with in 400 miles of Fairbanks Alaska I, reluctantly, take on the role of mechanic and care taker for this rig. I do have a fair amount of 240 wrenching experience (mostly wagons) and know enough to usually get into and out trouble. So I am far away from being an expert. So I really appreciate hearing everyone’ POV and ideas.

AKKevinT

Those readings are close to what I got on my 1983 240 last time I checked it some years ago at 140k miles. If they seem too high, I'd start by testing with a different test gauge to confirm the numbers. Could be some carbon buildup giving slightly higher pressures than a "clean" engine, but in reality - no worries.
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Son's XC70, my 83 244DL, 89 745 (Chev LT-1 V8), and XC60. Also '77 MGB and four old motorcycles. Long gone: 1981 244, 1994 940 and 1998 S90.