Bugout4x4

It needs to be nailed down for sure. If they are handing out the wrong part and application this needs to be known.

Short historical story about this type of situation...

Back in the late 80's we only had one parts store in our little town. It was a Napa store and had just went computerized for part application and numbers. There were quite a few hot rodders who were running big block Chevys in the area at the time.

Well all of a sudden there was an epidemic of overheating big blocks in town. Everyone was perplexed by what might be causing it. The first connection made was that they all just recently got a new water pump. The next connection made was all the replacement pumps came from Napa and had the same part number.

Someone finally took the time to compare an old pump and one of the new pumps from Napa and found the problem. Napa's computer was distributing out water pumps for big blocks running in reverse rotation. It was universally applying a part number for counter rotating twin engine big block boats! So of course they were trying to pump coolant backwards through the engine and in this very hot area it was just not working.

Tbone289

Sounds about right... Great story!

cyclesick

Hi 4WD4EVER, I,m having the same issue you describe in this post. First: I am not a mechanical novice. I am an Ase cert. master tech, though I have been retired for some time now. I'm working on a '98 4.0 and with #1 at TDC on compression, (confirmed with the valve cover off, both #1 valves fully closed and the push rods down and able to be rotated easily with index finger and thumb), the mark on the cam gear seems to be 180 out from all the diagram I've seen. If I rotate the crank 1 full revolution so the marks are aligned it brings it to TDC on the exhaust stroke. In 30+ years of turning wrenches I have never seen this phenomena. Could you please tell me What you did to rectify this issue? TIA

97grand4.0

You may be waiting a while. It's a 3 3/4 year old post. Seems to me tho you're not seeing what you think you are.

cyclesick

Thank you for the prompt response. I realize this is an old post and the O.P. may not be available to respond. It's the only option I could think of in light of what I'm confronted with. As to you're response, I am seeing exactly what I've stated. I spent 30+ years in the repair industry and most of that time was in an engine rebuilding shop,(22years total), though I must admit that in all that time I've never rebuilt a jeep 4.0,( I guess that says a lot about how tough they are) . Please don't misunderstand. I don't want you think I'm being cross or flippant. I know exactly how to determine the stroke of the crank and the position cam by reading the position of the valves and the directional tilt of the rockers. This engine is absolutely at TDC compression stroke and the mark on the cam gear is exactly opposite from where all the diagrams say it should be.

97grand4.0

Sure no problem, just curious, what is it you're trying to do in the big picture here. ?

cyclesick

Well, to give you a little history; The jeep is actually a 2000 we bought for my wife 20 years ago from Enterprise rentals when it was 1 1/2 years old with roughly 34,000 miles on it. It has never given us any issues other than normal wearing parts, brakes, shocks, exhaust, the occasional radiator, heater/evap cores that kind of stuff. So, I've never had any reason to open the motor,(It still had the original water pump and thermostat that was in it when we bought it). Well, now at 110,000 miles it has all the minor leaks from the external gaskets that you would expect from a vehicle it's age. So, I decided to replace all the gaskets that were leaking starting at the top of the engine and working my way down to the oil pan and rear main. When I pulled of the timing cover I found I didn't like the look of the timing chain and that's when all the crap started. The first set I ordered had a cam gear that was complete wrong,( it had a notch in the inside diameter, for late "99 and up). That's when I found out that at some point someone had put a '98 short block in the vehicle( I can only assume it was the dealer that did this under warranty since Enterprise was the only other owner). I realized this from reading the date code on the pass. side of the block. Directly under the date code was an aluminum plate glued to the side with a mopar parts part # that identified it as a factory built short block. I then realized the rear main I had bought would not fit either. After straightening out all of that and getting the correct timing set and rear main, I turned my attention back to the task of replacing the gears and chain. Upon rotating the engine to bring it to TDC I realized that #1 exhaust valve was fully opened when the timing marks are facing each other and booth #1 valves only fully closed when the cam gear mark was 180 degrees from where the diagram says it should bee. I've found that this is not entirely uncommon. I've been on several other jeep forums and found there have been others who've had the same issue. On every one of the other forums at the end of the thread the O.P. announces that they worked it out and have arrived at a solution but none ever offers to disclose what that solution is. 4WD4EVER was the only one to say to contact him if you run across this issue. So, I posted hear and also PM him hoping he'll get back to me. If you scroll down to the "related thread" at the bottom of this post you'll see a pic of that poster's crank and cam. That is exactly where mine line up with both #1 valves fully closed, both push rods completely down and #1 piston at TDC. In fact, I put a degree wheel on the crank and I am at dead center of the rock point. # 1 piston at TDC with both valves closed is very definition of TDC compression stroke. This, to me, is bazaar.