Napa Store says my 2.5 L is a limited edition

[98Chero]

I went into my local Napa Parts Store to ask them for a price of a long block for my 1998 2 WD, Auto, 2dr, 2.5 L engine, they said that there was only a few years that would fit that model and the price for the long block was outragous ! 1600. I went online and found several web sites that said the AMC 2.5 L was the same engine from 1991 to 2001... It seems that my engine has alot of blow-by and its causing oil to leak from the front seal...Yes I have replaced the pan and timing chain cover gaskets (taking special care to do it right)( installed the balancer shim to) and it still leaks oil. I'm thinking its because of the extra blow-by from the rings causing to much crankcase pressure. But my real question is if the 2.5 L engine long block in my 1998 cherokee is anything different than whats available online

Mike

 

[Bounty__Hunter]

Shouldn't be any different than any other '98-'01 2.5L engine.

Your engine can also build too much crankcase pressure if the CCV system is clogged and not properly venting crankcase pressure. This will force oil out past gaskets and seals.

How many miles on your engine?

CCV= Closed Crankcase Ventilation

 

[98Chero]

Shouldn't be any different than any other '98-'01 2.5L engine.

so 1991 to 2001 is not true?
There is two hoses coming from the engines valve cover, which neither seem to have a check valve in them, both of them are free (both ways). the one that is in the back of the valve cover goes right into the air cleaner box, while the one in the front goes into the carb/fi manifold. I'm testing the crankcase pressure just by removing the oil fill lid and feeling the presure coming from it on my hand. I need to know what the compression for the cylinders should be so I can test that tomorrow. The miles on the engine is 116,000 but I do regular maintance. the only thing I can add to this post is I had a fuel regulator valve failure a few months ago and it floodedd my cylinders with fuel several times, but I didnt run the engine that long before I fixed that problem.

 

[Bounty__Hunter]

Pull the vacuum line from the back of the valve cover to the airbox, at the airbox end. It should have strong vacuum sucking into the valve cover. If not, the CCV system is likely your problem.

Pull the vacuum line from the valve cover to the intake manifold, at the valve cover. It should be sucking into the intake manifold, this is where crankcase vapors are burnt. There should be a restriction orifice in this line, usually threaded into the valve cover. It's often plugged with carbon. If the CCV is not plugged, may have a collapsed or broken line somewhere.

 

[Bounty__Hunter]

'95-'96 saw some minor changes such as fuel rail, belt routing, etc. I would stick as close to '98 as possible.

 

[98Chero]

The CCV system is working properly and is very interesting, it pulls a vacum from the intake manifold and replaces the air in the valve cover with the hose that comes from the air cleaner box with clean, fresh, cool air. It probably helps to keep the rocker arms and componants cool... anyway the compression check turned out with different results. Cylinder 1, 3, 4= 125 psi, 2= 110 psi (triple checked) All the sparkplugs looked good and clean. Now i'm wondering if I have a cracked head or bad exhaust guide/bushing on #2 cylinder head ? I'm not sure what my next step should be. any idea's

 

[Bounty__Hunter]

Nope, don't know much on engine building or specs. Don't think the CCV is for cooling the valvetrain but for a clean fresh air intake to the crankcase.

 

[98Chero]

Today I put a few onces of 30/w oil in cylinder #2 and it changed the compression from 110 psi to 190 psi, all things considered the engine runs pretty good...hate to tear it down if there is a simple solution out there.. or a way to narrow down the problem. It would be nice if they made a telescope thingy that I could put into the cylinder thru the sparkplug hole and get a better veiw of the cylinder wall. Luckiy this not my primary jeep anymore, I have another one... I guess this problem will keep my wife off the road aleast...and save lives

 

[carnuck]

Change just the bottom end and any '84 to '04 2.5L will work. The head is where the biggest changes were made. I switched mine to 15W50 synthetic oil and the blowby disappeared at 200,000 miles.

 

[Bounty__Hunter]

They do make scopes to inspect the cylinder through the spark-plug hole, check with an engine shop.

 

[98Chero]

Bounty__Hunter
No scopes available in my area!

Change just the bottom end and any '84 to '04 2.5L will work. The head is where the biggest changes were made. I switched mine to 15W50 synthetic oil and the blowby disappeared at 200,000 miles.

carnuck,
are you saying you had an engine with blowby problems and added 15-50W Synthetic oil to it and it cured the problem and everything was cool and groovy when your engine hit 200,000 miles ?.

I was looking at a KW vented oil cap to releave some of the crankcase pressure till I can find a low mile replacememnt engine or a rebuilt lower end. as a last ditch effort to do something with the available materials I had, I increased the size of the orfice hole coming from the intake manifold hose to hopefully pull more presure from the valve cover area...Hey BTW This is Arkansas and I live at the end of a long dirt road :shades:

 

[carnuck]

Bounty__Hunter
No scopes available in my area!



carnuck,
are you saying you had an engine with blowby problems and added 15-50W Synthetic oil to it and it cured the problem and everything was cool and groovy when your engine hit 200,000 miles ?.

I was looking at a KW vented oil cap to releave some of the crankcase pressure till I can find a low mile replacememnt engine or a rebuilt lower end. as a last ditch effort to do something with the available materials I had, I increased the size of the orfice hole coming from the intake manifold hose to hopefully pull more presure from the valve cover area...Hey BTW This is Arkansas and I live at the end of a long dirt road :shades:

It didn't totally clear it out, but it's more livable. Only takes 1 quart / 1000 miles now.