1991 motor question

[headsup]

Since my purchase last fall, I have put about 5,000 kms on this 1991 SE PF.
It just rolled over into 200,000 kms.
I have noticed some hesitation upon acceleration, but unpredictable as to when or why.
It's not the perkiest PF I've driven for sure.

when I bought it the oil was topped up, and new.
I just checked it, and it's still topped up and a nice golden colour.
It clearly doesn't burn or leak a drop.

I had it at my mechanics this afternoon asking about it's hesitation, and sometimes it feels like it lacks "power".
He's not a Nissan mechanic, but he di tell me he checked compression in 2 cylinders and they were both between 50-80 lbs, which he felt was low.
He said the plugs were new, but thats as far as he got.

I asked how such low compression wouldn't be indicated by oil consumption or use.
He thought, if the vehicle was sitting for a while, the compression rings may have seized, where the oil rings didn't.

Does this sound right to other owners on the forum?

I will be taking it to the local Nissan and PF expert soon for a more in depth diagnostic.
How ever if that IS the case, with more of the cylinders, can those compression rings be freed up by pulling the plugs and injecting the appropriate product into the cylinder and let sit?

Local mechanic suggested an oil additive.
any help or advice much appreciated.
thanks.

[smj999smj]

50-80 psi of compression is low. Is that just a dry test or did he do a wet test, as well? Usually if a ring gets seized up in a piston groove, it's often the oil control rings rather than the compression rings. A cylinder leakdown test would help show where the compression is going. As far as soaking the piston, I would probably use Seafoam. Low compression can be caused by other things as well, including bad lifters, weak valve springs, bad head gasket, burnt or poor sealing valves or cylinder walls being washed down with fuel (ie leaking fuel injectors or excessive fuel pressure).

[headsup]

After having my local all round mechanic guy look at the 91 PF SE, i didn't like his diagnosis, so I took it to the expert, who has been repairing Nissans and rebuilding the older ones for years.

he's a real gem, and showed huge respect for my 23 year old Pathfinder.
BESIDES that, he pulled out the crappy Champion plugs and installed a set of the best NKG ones there was, as well threw out the crappy airlifted, and put in the Nissan one, and showed me why.

While he was at it, he did a compression test.
All 6 cylinders came in at between 173-180.
floors and frame all excellent, needs a winter thermostat, maybe timing belt kit.
Says to undercoat it again, and it should last another 20 years...

not sure how to post pics here, but it's a red sporty thing, and after having this expert work on it, he will be the only one to do so from now on.

Now if I could just find the old 1" & 5/8 trailer hitch assembly.....
(apparently, they were made by Putnum, who have gone out of business.....

[smj999smj]

Putnum #30018 was a 1-5/8" ball mount, but good luck finding one!