First time opening an engine, help me out! - JeepForum.com

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post #1 of 48 Old 10-20-2015, 07:18 PM Thread Starter
Mp5ben
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First time opening an engine, help me out!

Bought a 4.0 to do a swap for the CJ to get a more modern engine and MPI. Bought the thing sight unseen and went to pick it up, seller said it "ran great with good power" and that it was from a 92 XJ with 82k. I get it home and put it on the stand and start going over it when I try turning the engine over...it moves but it gets stuck.

I don't want to to force it to hard since I'm not sure what's binding up. So at this point I'm thinking I got screwed. I proceed to take off the valve cover and I see just the most horrible sludgey oil I've ever seen. It looks as if it's been cooked on the head. I know this can't be good.
Then I take off the oil pan which, I find nothing in the pan thank goodness. And to my untrained eye, nothing looks broken, sheared, snapped or bent. I do notice some rust patches here and there, including some very small patches on the shaft and on one (as far as I know) cylinder wall, 2nd cylinder I beleive.

Coming to you all for some guidance. I have yet to buy a FSM because I haven't found a good source for one but I'm looking. I'm willing to learn about working on this engine since I'm this deep and I've always wanted to learn anyway. So I have some photos and just need some help on where to start looking next.












01 WJ, 4" lift, Front Adj lower and upper,4.0, D30,D44a
86 CJ7 Laredo, 258, T5 D30 AMC20, 2.5" lift
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post #2 of 48 Old 10-20-2015, 07:30 PM
Ken4444
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Quote:
Originally Posted by Mp5ben View Post
... when I try turning the engine over...it moves but it gets stuck.
Did you remove the spark plugs before turning it?

"I give you a republic, if you can keep it." - Benjamin Franklin
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post #3 of 48 Old 10-20-2015, 07:37 PM
Kalimni
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Question: How did you attempt to turn the engine over, and were the spark plugs in out when you tried? With no plugs, the engine should turn fairly smoothly using a wrench. With plugs in, you would probably hit a tough spot every time a piston started on the compression stroke. If you were turning it over with the starter, it shouldn't have stopped. You may have some rust in the bearings and/or in the cylinders. Seeing as you found some rust, I would guess you the engine has been sitting dry for sometime. It would probably be a good idea to do a rebuild regardless.
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post #4 of 48 Old 10-20-2015, 07:38 PM Thread Starter
Mp5ben
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Quote:
Originally Posted by Ken4444 View Post
Did you remove the spark plugs before turning it?
Yes sir! I tried with them in, and out. Also, when turning the engine between the two points before it stopped, air would "whoosh" out when turning it over, it came from the bottom end. Worth noting I think

Kalimni:
I'm using a breaker bar on the main pulley. I can only get so far turning to the right before it stops. Turning left (CCW) Turns smoothly till it seizes up again and the nut on the main pulley loosens up.

01 WJ, 4" lift, Front Adj lower and upper,4.0, D30,D44a
86 CJ7 Laredo, 258, T5 D30 AMC20, 2.5" lift
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post #5 of 48 Old 10-20-2015, 08:01 PM
STJP
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Should only turn it CW
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post #6 of 48 Old 10-20-2015, 08:34 PM
mamllc
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I've never seen under the valve cover of one of those, looks just like an old Oldsmobile.

While you have the valve cover off check all the valves to see if one is stuck open. Quite possible if the engine has been sitting for a while. If you find one tap on the top of it with a hammer and a block of wood, sometimes that will break them loose. Was there any water in any of the cylinders? Rust in a cylinder can do that. Got a bore scope?
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post #7 of 48 Old 10-20-2015, 08:38 PM
wadewen
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It's a shame that they gave it to you with the conditions you're finding. Can I assume that the sludgy oil in the head also had a strong burnt smell to it? If so, sounds like it got run out of oil until it died. That would likely result in the need to do a full rebuild with bearings, rings, etc. It's also possible that the cylinder walls got warped and/or scored along with the head.

I would second the note from the person above that said the surface rust on the interior machined surfaces indicates it sat for a while.

I'm thinking you'll need a good shop to evaluate the block and head to see if it's a candidate for a rebuild as a starting point.
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post #8 of 48 Old 10-20-2015, 09:01 PM
scooby533
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Ben, not convinced it's seized yet. You need to find what it's hitting. It's either a valve, a piston, a connecting rod, something in a cylinder or maybe you bolted the enigine stand up wrong. Is the flex plate hitting something? Process of elimination!
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post #9 of 48 Old 10-20-2015, 09:01 PM Thread Starter
Mp5ben
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I didn't know to not turn it CCW. thanks for the tip.

I took the rockers and push rods out to see if that could be the problem. No luck so far. I will try tapping the springs to see what happens. Can such a small amount of rust really cause a whole engine to lock up? When I had the engine upside down I noticed the time chain had quit a bit of slack. Not sure what's normal so I'll try to take some photos of that next time I'm in it. No water in cylinder, ot bore scope but so I'm just looking through the spark plug holes. Strangely I didn't notice a burnt smell that was obvious, I got a whiff of it here and there but even with my nose to the valves I couldn't pick up on it. There was a good amount of oil still in the pan when I dropped it. Probably not enough though

While I was removing the rockers, each one was so torqued that the rocker bridge bent, each one is skewed now.

01 WJ, 4" lift, Front Adj lower and upper,4.0, D30,D44a
86 CJ7 Laredo, 258, T5 D30 AMC20, 2.5" lift
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post #10 of 48 Old 10-20-2015, 09:08 PM
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I've seen worse sludge under the valve cover and the engine ran fine. It's more an indication of lack of maintenance. Since you have it torn down this far I'd pull the head and inspect the bores. If you can get it to turn over without the head I'd put in a fresh cam and lifters and plop the head back on and run it.

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post #11 of 48 Old 10-20-2015, 09:09 PM
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Almost forgot to say I don't see any issues in the pics that would bind the motor unless it's the rusted areas that are grabbing hold.

I'd go ahead with taking off the head. Here's a link - not from the service manual though

http://www.howacarworks.com/engine/h...-cylinder-head

By the way, you can find the service manual on line for free usually.
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post #12 of 48 Old 10-20-2015, 10:22 PM
CSP
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I've found XJ factory service manuals on www.naxja.org for various years. Any '91-95 FSM should cover that engine with 99% accuracy. It didn't change much in those years.
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post #13 of 48 Old 10-21-2015, 03:18 AM
Matt1981CJ7
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It seems you are getting the same advice as you got on your other "First time..." thread. GET A MANUAL!

We can't spoon feed you every step of a engine overhaul procedure.

Matt
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post #14 of 48 Old 10-21-2015, 03:30 AM
wadewen
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Glad to hear that it doesn't smell like they burnt it up. You should find something that's binding it when you take the head off then. Also, I couldn't tell from the pics if every piston rod is in good shape. A broken one could explain your issue.
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post #15 of 48 Old 10-21-2015, 05:26 AM
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What Matt said! You've asked and we've answered.

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