Fred258

Bought 98 Cherokee 4.0
155k miles
with low compression #1 cylinder
Found broken valve spring
Replaced
$250 parts and labor
Had low oil pressure < 5 @ idle
Drove about 1 week and overheated

Towed to mechanic
Low compression #1 again
Water pump failed
Blown head gasket
Pull head, clean, test and plane
New head gasket
New valve seals
New water pump
Oil change
All parts and labor $530

Drive for 2 days and had episodes of starving for fuel. It had set for about 3-5 months before I bought it so I am thinking sediment in line or tank. I add seafoam and within 20 minutes check engine light was on. Now had a pronounced miss at an idle.

Find plug wire arcing so I changed plugs wires cap and button. Still had miss oil pressure still low. Removed and cleaned sending unit changed oil to 15w40 and add Lucas oil treatment. $100+
Still had miss.

Removed and cleaned IAC and miss continued. So take it back to garage.

Low compression on cylinder #1!!!!!.


Just
Empty
Every
Pocket

All new valves and springs next along with sending unit or oil pump or why not just do both...

XJwonders

Welcome to the forum

Fred258

Well thanks that's a lot better reception on the first time I got when I posted here I appreciate the hospitality

rabblerouser

Did you check for worn rings? If you keep having low compression after having all the head work done and new gaskets id be looking at lower end for the issue. Worn rings or possibly a cracked block?

PocketsEmpty

$530 for all of that work at a shop? WOW. All of that would easily cost three times that in my area.

Any reason for running 15w40? Isn't that kind of heavy for a 4.0? Anywho, it sounds like you might have some bad rings.

Fred258

I have reached the end of my limited knowledge. Mechanic said he floated the valves with air and still lost pressure so he is thinking maybe an exhaust valve.

The work was done by my best friends son, he has his own shop. The trade off is I do not get it fixed as fast as I like. He is like a nephew to me.

I have had not loss of oil just pressure has been low from day one. No oil residue or oil smoke. So would rings be out of the question?

I doubt block cracked no loss of coolant.

Fred258

Sorry forgot to give reason for 15w40. High mileage vehicles often use it I am told. It did bring the pressure up to 40+ until about 20 minutes of running then at idle drops to around 10

Fred258

Don't know really what to think. I appreciate and ideas or thoughts. I now have about $1500-1700 in it and am second guessing my purchase

DougyFresh

have him do a leakdown test on it. Hissing sound in intake, intake valve. Hissing sound in exhaust, exhaust valve. Hissing sound from oil cap, rings.

As far as the oil pressure goes, it sound like you need to replace the oil pump.

Fred258

Pump or sending unit or maybe even both. Checking oil gauge against mechanical gauge tomorrow. When he adds the air it leaks through the intake. He says it had to be valve. He went college for this I hope he is right.

DougyFresh

did he lap the valves while he had the head off? he should have...

Fred258

Don't know we took the head to a machine shop and had the work done. That guy did the valve seals so would that have been standard to do at the same time?

DougyFresh

should have, but I would check with the machine shop to be sure.

Fred258

OK sorry took so long to return here but so busy these days.
Compression was at 50 on number 1 because if a small burn on valve. Now the motor did not have ANY problems with compression until SEAFOAM. So I guess I will not be using it ever again. Lapped valve and now all 6 at 150.
Cost $115

Bought the Jeep for $600
$250 in first "fix"
$530 in second
$125 plugs wires cap and rotor button.

So right now I have about $1600 in it.
Thanks for all the suggestions and help. I really do like driving it. I sold a 98 Honda Accord that I bought new for $1400. It had 254k miles on it to buy this Jeep so I have about $200 out of my pocket and look forward to driving it for several years.

Fred258

Forgot to mention the oil sending unit was bad mechanical gauge show did was pumping at 50 pounds