First post.
Okay, is it even possible that a Disco would run at an average of 75 PSI?
I rented a gauge and did the test both cold and hot, same thing.
Cylinder pressure ranged from 70-90 PSI.
The car seems to run fine, no overheating, no water in oil, coolant level is full, etc.
I do think I can smell coolant in the exhaust (sweet smell), but I also had a very bad washer fluid leak that was getting all over the place and does tend to smell similar.
I just can't imagine that the pressure is accurate.
I'm going to try and find another gauge and recheck.

On a positive note, I was about to put a new tranny in and as a last resort I put half a bottle of Lucas tranny fix in and it actually seems to have helped - I am not usually a believer in additives.
Now I am going to do the full filter/fluid change and see if I may have saved it.

 

If I remember correctly, you should be seeing 135-145 psi? But don't quote me. You may want to look through the RAVE full version, it may be in there.

 

Low compression could mean many different things. How many miles? Is the timeing correct? ETC. ETC. My father-in-law has a 1986 Ford Ranger with 423,000 miles on his four banger engine. The compression is just under half of what a new engine should be. The engine still runs smooth and strong.

 

While I have not done it with my Disco 1, I did use Lucas tranny fix for over 150K miles on a Montero Sport that I sold with 292K on the clock. I believe it works by increasing the viscosity of the fluid, rasisng the pressure, and returning shifting to normal. Another product to consider is "Dr. Trannys Shudder Fix". My tranny shop is located next door to the largest auto auction in the area, and they keep a couple of cases by the door. It works, not sure how long, maybe that is why the used car sales weasels like it. Have used in a couple of trucks at the office that we did not have budget for tranny replacement.

 

Recheck with a different tester, not all cylinders can be that low.

 

Well, I re-checked with another tester and the 3 I checked were the same, so I stopped there.
Added a little oil to 2 of them, one increased to 90 PSI, the other didn't change.
So now I am really stumped, the truck runs fine, no obvious missing, smooth idle, no oil burning, no obvious coolant loss.
I was ready for a low reading or two, indicating the need for a HG.
But this suggests I may need a complete overhaul, and with the lack of any symptoms, I am likely to forego for now and just run it until a problem actually occurs.
Anyone heard of an engine with low compression running "good"?

A somber ending to an otherwise great father's day.

 

LRD2&ME,
Sorry I missed your post earlier.
The truck has 154k.
I just bought it a week ago.
I have no other symptoms other than low compression and the possible smell of coolant in the exhaust (with the leaking washer fluid all over the exhaust and now my dripping coolant all over the lower block when trying to swap out the thermostat this is difficult to evaluate now).

I have not checked timing, and am confused how this would effect compression?

Still working through DiscoMike's suggested 60K maintenance.
To date:
Lubed drive shaft (only 1 fitting on rear shaft?)
New wires and plugs (Bosch +4)
New tranny filter (yeah, that sucked)
oil and filter
Quick coolant dump and refill (old coolant was orange?)

 

How'd you get your trans cross member out? I had to quit

 

I never did get the crossmember completely out - just yanked, cursed, and pried down low enough to get the pan out.
It was a very long day!
I 1st tried to get the pan out without completely removing the cats/pipe.
Not possible IMO.
Eventually caved in and dropped the pipes from the manifolds, giving me enough room to pry the cross member down low enough for pan removal.

And as expected, getting the pipes reconnected by myself was a PITA.
Beer helped a little, I think.