Crankshaft Replacement

Has anyone ever taken out their crankshaft without removing the engine from the truck?

My repair manual indicates that it is possible to replace the heads, camshaft, bearings etc without removing the engine from the vehicle.
Of course I would have to take out the radiator and remove a lot of external stuff.

It even indicates that I can replace the crankshaft bearings without removing the crank. Done from the bottem with oil pan off.

Should I find that my crank is "out of round" or in need of machining or replacement; is it possible to take it out the bottem with the transmission still bolted to the engine and the engine mounted in the truck.

I litterally intend to overhaul this thing in my driveway with a minimun of tools. No engine crane or engine stand.

2000 XJ 4.0L electronic fuel injected with an automatic tranny.

I'm serious, but it is ok if this idea gave you a good laugh

Any tips or coments would be appreciated

"minimum of tools" and "engine overhaul" spells lots of headaches.

You aint getting the crank out without unhooking the tranny. You can do just about everything else with the engine installed, but you have lots of things in the way. It's much easier to get to the #6 cylinder and camshaft, etc with the engine out. Once you've got the head off, its not much more to pull the engine anyway.

I highly recommend borrowing an engine crane and stand. Maybe buy the stand relatively cheap from Harbor freight and rent the crane locally for cheap.

Why do you want to overhaul anyway? What's the issue with the engine? With minimal experience and tools, swapping in a good used or refurbed engine or shortblock is sometimes cheaper and certainly quicker.

Smurfitranger said:

Your oil pressure problem sounds like what I got after my Jeep dealer serviced my jeep and forgot to put oil in it before he test drove it. I had a really good engine with good fuel miliage before this. Ever since then it still runs, but with 3 mile per gallon less miliage and the oil pressure problems that you describe.

Click to expand...

Ah! I found your other post. I'm assuming you've verified the low pressure with a mechanical guage? The oil pressure sender is a notorious liar and they occassionally get whacked and damaged changing the oil filter. Speaking of filters, avoid Fram as they've been know to cause oil pressure issues as well.

Any funny noises when the pressure drops? If the pressure drop is real, I'd consider dropping the pan and replacing the oil pump (which might just have a sludged up pickup screen). From there it's not too difficult to replace the crank and rod bearings, but I would use some plastigage to measure the clearances first. I doubt you'll need to do anything to the crank itself unless its torn up. And of course while you're in there the rear main seal...

I once re-ringed, honed and replaced a piston in my 4-cyl Wrangler, so it can be done. I think that engine was built on a monday or friday as half the rings were upside down.

-Chris

Yes, it's possible, but not advised unless you have a LOT, and I do mean a FREAKING LOT of patience, lol. I've done it before and I won't do it again. You have to be really careful not to scratch/gouge the crank journals going in, and it will be interesting to do that from under the Jeep with the front axle in the way, trying to bench press the crank up into place, then holding it steady while you get the bearing caps in place.

Have a garage/carport/large tree handy? For years Dad and I just used a cable puller/come-a-long hung off a garage rafter to pull engines. Yep, even big block Chevys and a couple Jeep 258s. I've done this a couple times on the farm with a chain fall and a big arse tree limb too.

Pull the engine (IF) the crank is wasted. You will need a replacement crank and any other crank (used or reman) should be checked for clearance on the mains and rods. This needs the block inverted for the mains anyway.
(IMO) If the crank is gone? Get a used motor,

There is a Harbor Freight a few miles from my work.

I have been using Fram Tough Gaurd. I'll stop by NAPA and try one of their filters.

I had planned to install some sort of mechanical gauge when I changed the oil pump this summer. Am looking at a Melling high volume pump.

I have not noticed funny noises when the oil pressure drops.

Before the mechanic screw-up my engine did not use any oil in a 3,000 mile oil change interval with 10 W 30. Now it uses about a quart with 20 W 50. While many would say that this still is not bad for an old engine, the dramatic change indicates damage that needs repaired to me.

I always end up walking at the worst possible time or place when I ignor such repairs !

The above comments are appreciated! Thanks

Put your mechanical gage in now to verify low oil pressure. If you really have low oil pressure, I believe the lifters would clatter. Bad bearings do not use up oil. That would be rings, valve guides, or leaking through gaskets/seals. Without doing research on your old links, how bad is your oil pressure?

Oil pressure starts out around 40 on cold start.

Stays in that area until the oil warms up. Then runs about 37 cruising down the highway @ 2000rpm.

What concerns me is that after driving 20 minutes or more that when I stop at a stop light that it will drop to zero while I am sitting there with my foot on the brake and the auto tranny in gear. (RPM will drop to about 400) I have to put the tranny in neutral and put my foot on the gas to increase RPMs to get some oil pressure back.

I never had this problem before the mechanics mistake. Oil pressure used to be about 60 and did not drop clear to zero at warm idle.

Compression tests build pressure through 7 turns. My repair manual does say that is an indicator of wear in the rings. One cylinder @ 115 , a couple @ 120, the rest are a little better. If I remember right: factory spec should be 120 to 150. I think my highest one was 135.

Leak down test showed only minor loss at the low cylinder.

Have you verified that the low pressure reading is real, and not just a bad oil pressure sender? They are mechanical inside and can wear out and give the symptoms you describe. I'm skeptical that its really dropping to zero as you normally hear valve clatter when that happens.

I Have not verified that yet. I'll need to do that before I decide exactly the actual work that I need to do on the engine.

Don't verify it - just get the Fram off it. Put any other filter on and see if the problem persists.

A quart in 3000 miles is a noticeable change - but something many of us just live with. Rebuilding costs run $800 to $1,600, depending on bad components and machining.

I also suggest you get a compression tester and verify the suspicion that ring or valve guide damage actually exists. That's the only two ways oil can get into the chamber to go out the tailpipe. Any other way results in oily antifreeze or a greasy spot where you park.

If there is ring damage, $800 will buy you a lot of Restore to pour in every oil change, and you won't have to tear it down now. You can accumulate parts and install a new engine at your convenience, with a comfortable cash flow.

Change the filter now to confirm the oil pressure problem, compression check, and then, cash flow analysis. That's how pro's figure it out.

First thing to do is to screw in a mechanical gage.

Got the Fram filter off. I put in a NAPA Gold. Also replaced my gauge sender with a sender from NAPA.
My oil pressure on the gauge does show more pressure now. It now shows 37 to 60 running down the road @ 2000 rpm. (Varies back and forth). Before the pressure stayed around the 37 to 40 range on the highway.
Cold start pressure at idle is a little higher.
After a half hour of driving the pressure now drops to about 12 in gear at idle with my foot on the brake. ( I believe that is with-in spec) So far it has not dropped to zero since I put on the new sender and filter.
I went back to 10w30 oil as that was origional spec and you were questioning the sender and filter.

Would it cause you to use oil if your oil is too thick?

I don't have any oil spots in the driveway where I park the truck. There is a film of oil on top of the valve cover. Apears to be coming out of the rubber groments in the front and rear of the cover on top.
Slight leak at rear of crank.
oil has flowed back onto the tranny from the engine.

You oil pressure sounds much more normal now. On the oil leaks, having a little on the valve cover seems typical. You might want to feel the back of the block and see if its wet. Sometimes the valve cover leaks and it looks like a rear main seal leak. A leak around the oil filter adapter (piece the filter screws into) is common as well. You might check that the rear line coming out of the valve cover is clear. If that is plugged up, it can cause excessive blowby (oil on air filter) and make some leaks worse.

Ok, I'll check those.

Thanks !