Hi all,

I just picked up a '96 Laredo off of Craigslist and am planning on fixing it up a bit. Started with a compression test and got something I've never seen before. I have consistently high compression on all cylinders - tested multiple times with two different gauges.
175, 180, 180, 180, 185, 185 (From 1-6, in PSI)
Everything I can find says I should be looking at 120-150 PSI.

I've driven it a few hundred miles and it has no noticeable issues from the engine. I did my best to look through the spark plug holes for residue. Didn't see much, although it's not much of a view.

Any thoughts?

*edit* Should probably add, that's with 7 compression strokes on each tests, and no oil added to the cylinders. Compression rose quickly on the first few strokes and started leveling off around then 5th.

 

If it runs fine don't worry about it. Mine tested out at 175psi, give or take a few across the board, never had a bit of trouble and still running great at 232k miles.

 

consistency across cylinders is what really matters. Your numbers are good.

 

Chrome rings on nodular iron cylinder walls that are vertical? With the low rpm these engines run at, I wouldn't be surprised if there was still some hone scratches in them. I saw a VW Rabbit with 140K on it that still did.

The 4.0 is long lifed because of a very well balanced crankshaft supported on 7 main bearings. I can't, however, say as much for the pistons. Put forged pistons in it and it'd last forever.

 

Those numbers are great, I'd be happy as hell to see such a good balance

 

Has the engine just been rebuilt ?

 

Thanks for all the info! No recent rebuild as far as I know, but it's had about 5 owners from what I can tell on the VIN report, with me being the 3rd since 2014 so I can't be sure. The guy I bought it from didn't have much to tell about it.