Worn out bearings sound...Water Pump or other?

[Motorhead X]

My MJ has been making a fairly loud sound that indicates some type of worn out part. It is the worst when I first start the cold motor and goes away as the motor warms up. My first thought was something in the bottom of the motor, which would be the worst case scenario, but then I thought it could be the water pump. So I am considering replacing the water pump this weekend while I have the radiator out which also needs to be replaced.

 

Any other suggestions on what could be making the noise? It sounds kinda like a diesel knock or marbles rolling around in a steel can. I figured if it was something in the bottom (or top) of the motor, it wouldn't completely go away as things warm up. The water pump is not currently leaking and I have had NO overheating issues. I am only replacing the radiator because it has a slow, weepy, leak at the base of the trans cooler connection. I also plan on replacing the thermostat while I am in there.

 

Thanks all.

[Green Mesa XJ]

Might grab a automotive stethoscope.
Easier to listen to the accessories as they are turning. Don't forget the distributor can be a source too.


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[fiatslug87]

You can also use a long screwdriver, place your ear on the handle and the tip on the water pump, valve cover, engine block, etc. to locate the sound.

[Strokermjcomanche]

Pull the belt off and check each pulley / accessory for play or noise . You can also ( with everything clear including your hands ) start the COLD engine up with the belt off to see if the noise is pulley / accessory related or engine related . 

[Motorhead X]

These are all good suggestions. Thanks.

 

II decided to crawl underneath right after a cold start this morning. The noise is much louder near the back of the oil pan than it is at the front of the motor. So until further investigation, I'm probably ruling out the water pump and accessories. This has me concerned. It just sounds darn right ugly and it really bothers me knowing that something is going south. It still runs pretty good otherwise though, so we'll see.

 

 

[Minuit]

Check behind the little inspection cover at the front of the bellhousing. It's extremely common for the flexplate bolts to come loose and cause a knocking noise. I had this and it sounded just like what you're describing.

[gogmorgo]

Ditto on the flexplate. Although when mine was making noise, it was actually working its way to a two-piece deal. This was (in my mind) caused by another problem that caused similar noises, the bellhousing bolts backing out of the engine block.

[cruiser54]

https://www.cherokeeforum.com/f51/checking-cracked-flexplate-172081/

[Motorhead X]

Thanks everyone. I opened the inspection cover and all four bolts are flush. I couldn't get in there to check tightness because one of the larger cover bolts is backwards and won't come out without removing the exhaust, but I'm fairly confident that the interior bolts are ok for now. The more time I spend under there, the more it sounds like something in the block.

[Minuit]

Can't be sure till you get a wrench on it. If I'm remembering correctly (this is 5 years ago now) the bolts looked fine until I tried to turn one. Can you not bend the cover a little bit to slip a tool in?

 

WTF were they thinking when they put that bolt in? Mine was that way too. 

[Motorhead X]

I went back under and checked the bolts. They are tight. It was a good idea to rule it out for sure.

[jeeppapa]

These are all good suggestions. Thanks.
 
II decided to crawl underneath right after a cold start this morning. The noise is much louder near the back of the oil pan than it is at the front of the motor. So until further investigation, I'm probably ruling out the water pump and accessories. This has me concerned. It just sounds darn right ugly and it really bothers me knowing that something is going south. It still runs pretty good otherwise though, so we'll see.
 
 

You could pull the valve cover make sure every thing is tight and within spec. You can pull the pan and start wiggling things get on the net and find out how to diagnose it from the bottom with the pan off. If it's a piston pin that's a lot easier to fix then changing the motor. If you don't know about piston slap get informed on it. So you don't miss anything. Another option is to pay for a diagnosis then fix it yourself. I think I can give you a place to work on it up here in Palmdale. I'm on three archers up here. I can help you out with some tools and know how too. Hell you could spend the night if you have too. I'm kind of FUBAR rite now with my knee replacement. I'm getting better every day but I would be limited. If it's the worst case and you need a replacement. I've got 2 HO long blocks I've been sitting on both have about 130,000 on them. Ones out of a 96 the other out of a 98. Don't lose hart though. I have had the worst engine noises turn out to be an easy fix. I've got s mechanic in that I would trust with anything. He owns two shops one in Santa Clarita the other in the valley off the 5. The only thing is it's a 2-3 day wait to get your car looked at. He runs an honest shop witch is like gold here in LA. Like I say don't let it get you down. Just think of it as a challenge it will work out.


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[jeeppapa]

I had the flexplate issue on my 89.


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[Motorhead X]

Thank you jeeppapa. I am feeling a lot better knowing there are some options. It would be really helpful to have a decent spot for me to work and your advice along the way.

[cruiser54]

Flexplate could be cracked.......................