So my Fathers '99 Ranger dropped compression in the number 4 cylinder of his 4.0 ohv. I found a low mileage 4.0 ohv from a '96 Explorer and dropped it in. It runs great, good compression, perfect idle, no check engine light, no codes, it drives like a new truck. The problem is an extremely loud ratcheting sound coming from what seems like everywhere. The gentleman who sold us the engine swears it was perfect when removed from the rolled Explorer. It spent 8 hours at a very reputable shop after the swap and they could not find the cause of the racket.

I used as much of the ranger equipment as possible. Including all wiring, waterpump and fan, alternator, a/c, upper intake and fuel rail. However, I left the Explorer Crankshaft position sensor in the engine, and used the Rangers Camshaft position sensor since it was a 2 wire instead of the Explorers 3 wire. Could this be the problem? The shop I go to said it should not be a problem, but they are not too experienced with engine swaps.

A new flywheel was required as the Ranger had an 8 bolt crank and the Explorer was a 6 bolt. The new flywheel is the same thickness and same amount of teeth as it's elder. I also replaced the external torx head flywheel bolts with new hex head bolts. A new clutch kit was also installed. A clutch issue was suspected, so I removed the tranny but the clutch and flywheel had perfect wear and the noise persisted. I also checked the pressure plate and the inside of the bellhousing thinking something might be hitting. Everything looked A-OK.

The noise continues without the serpentine belt installed, thus eliminating any of the front dress accessories. I have removed the valve covers to check for foreign objects, bent pushrods, broken valve springs or anything obviously wrong, nada. Everything worked as it should when turning the engine manually. Starting the engine without the valve covers showed nothing new but a big puddle of oil on my floor.

My only other thoughts could be a stubborn collapsed lifter. We idled the engine longer than it should take to pump up a lifter. The truck has been driven 20 or so miles and still no change. At $37 per lifter and more of my time wasted, I was hoping someone could help me out with any possible issues. I hastily spent 10 hours to R & R the tranny suspecting the clutch, I really don't want to pull the lifters to see no improvement. However, all I can think of at this point is to install new pushrods(a little more than $5 each) and reuse the Rangers lifters(which were fine when that engine was removed).

Please help!! Along with half a dozen professional mechanics, 2 confused parts store clerks and a frustrated me, we would love to find the issue.

Thank you,
David

 

Just a guess - is your starter drive not releasing from the flywheel?

 

You can pull the starter after the engine is running. To see that is problem

 

Sorry it took awhile to reply. The starter was checked by the shop and works fine. The starter was the one from the Ranger and we never had any problems with is prior to the engine swap. I am so baffled, I don't know what to think.

 

My '91 did the same exact thing after I installed a used engine.

Initially, it didnt make any noises so I let it idle for about 30 mins and then took it for a short drive. About 3 or 4 miles into it, the engine begain making a horrible ratcheting/knocking noise just like you describe. I shut it off for the night and the next morning when I cranked it the noise was still there. It sounded strongest at the drivers side valve cover so I pulled the cover off expecting to find something broken or loose. To my amazement it looked perfect. After reassembling it, I cranked the truck up and the noise was gone. That was 4 years ago and the noise has never returned.

I believe my problem was a collapsed lifter as it vanished just as quickly as it began. In the past I have added as much as a couple quarts of transmission fluid to the crankcase on junkyard engine installs as top end noise is always a big problem on engines that have been sitting for long lengths of time.

 

Thanks for the info. I was hoping it might just be a lifter. I already checked and the ranger used the same lifters as the explorer so I will reuse those. Any idea why those boogers cost nearly $40 each?

 

It's because they're made from multiple pieces of precision ground high strength steel (unless you buy crap from China). Then there's the great American profit motive.

Be aware that mixing these used parts from different engines (or even mixing different positions in the same engine) can accelerate wear of the affected parts. It's because the parts are forced to re-breakin to their new location.

 

Just wondering if you found the problem? And of course looking for some similar help. As far as your cam sensor I am in a similar situation and looking for advice, I am installing a '98 4.0 OHV w/a 2 wire sensor into a '98 with a 3 wire sensor. Did you have to change the synchronizer or will the two sensors interchange? There was only 5 months difference between the build dates of the engines but a lot of differences. Thanks in advance.

 

Hi,
As a last ditch effort, I disassembled the engine thinking a bad lifter. I did not realize the cylinder heads have to be removed to get to the lifters. After removing the heads from the noisy engine, I found the reason why the it was sold for such a reasonable price, there was a bolt in the top of the #6 piston. I cleaned up the bottom of the head, replaced the piston with one from the old engine and lubed the hell out of everything. I have done some oil analysis tests since and everything is looking good a year and about 5k miles after the swap.

As far as the cps, I used the Ranger sensor in the Explorer motor. Dropped right in and is still working. I did have to remove the top of the sensor to clear the intake.

Good luck and let me know if I can be of any help,
David

 

Thanks very much I thought I would have to change the entire assy (sensor and synchronizer) but wanted to see if that's what you did.

 

I was just wondering when you
Dropped a 96 4.0 motor into your dads 98 4.0,you had to change from a 8 bolt hole flywheel to a 6 bolt hole flywheel? I ordered a short block for my 99 4.0 ohv motor and received one with a 6 bolt hole
Design for the flywheel and my old flywheel is a 8 bolt hole. So I'm wondering,do I need to buy a flywheel for a 96 which would have 6 holes and a different clutch? Thanks,Dan

 

I took the old flywheel down to the parts store and compared the options of flywheels for both years, then purchased the 6 bolt. It was worth it to pick up the complete clutch kit. The bolts are different, for the 8 bolt they are a torx, the 6 bolt are a hex head. I don't know if it is necessary to change to the heI did) but I could only find them at the dealer.
I did not know to check the slave cylinder (Dad's is a standard). If yours is a stick, check for leaks. I had the pleasant chore of replacing his a year later. For $25, it's worth replacing while your in there.
Hope this helps, good luck!