Re: Why are compression test numbers so high?
 

I would suspect your gauge if the readings are that high. Not that they couldn't be but that is unusually high.

I have had a couple at 200 but that is an engine with 30k on it. Try the tester on a couple of others to compare.

You could have some carbon build up causing some high readings. Maybe do an engine flush and run some expensive fuel system cleaner to get rid of the carbon build up on the piston heads. Maybe I'm talking out of my arse, but I think that sorta makes sense.

Re: Re: Re: Why are compression test numbers so high?
 

How many miles did the other Max have?

Well I did my new 95 today and it recorded 150-160 for 5 and 175 for 1 using the same gauge I recorded 200 on my 97SE.

There is nothing I know of that would cause unusually high readings and the higher the better indication of a good engine as long as they ALL are high. ie with 10-15 psi of each other.

If there was that much carbon build up to increase the compression that much, you'd be having some drivability issues by now.

You'd think the car would be pinging and knocking with that much carbon build up.

Another thing that may cause higher then normal readings would be oil in the cylinders caused by leaking valve stem seals. Does your car throw out a puff of smoke when it's started up? Thats a sure sign of valve stem seals and guides wearing out.

It's always been my understanding that you really aren't suppose to pay attention to the actual numbers on a typical compression gauge, but rather pay attention to the consistency of the compression across all cylinders. If your compression is similiar in all cylinders, then I wouldn't worry about it, but if one or two cylinders was 15+% lower than the others, then I'd suspect there might be a problem.


Dave

Re: Re: Re: Re: Why are compression test numbers so high?
 

103k

That's what I always base my readings on. Also, how about the method used to get the readings. Did you remove all the plugs, disable fuel/ignition to prevent starting, kept TB @ WOT, then record your pressures one cylinder at a time? Not doing it this way wouldn't it cause a higher or lower readings? Also how about the battery state of charge, wouldn't a fulley charged battery spin the starter faster which might give you a higher reading. Was the readings taken on a cold or hot engine? Cold equal loose clearance (rings, pistons, etc) lower compression readings. Hot visa versa, maybe?