Timing Chain...

So I was driving my Jeep this morning, started and ran fine. I was going to get on the freeway and I had a sudden loss of power. FYI, I was already in 5th going freeway speed, I wasn't revving the crap out of the engine. Felt like when a engine looses fuel pressure. Before I could look over my gauges and manage my way to the shoulder the engine had already died. Tried cranking it and noticed it sounded funny. After it was towed to my house I checked fuel pressure, injector pulse and spark. Got spark off the coil and not off the plug. Took the cap off and checked for carbon tracking, cracks and burns then checked for distributor rotation. Found no rotation so I pulled the oil cap and checked for rocker arm movement and no movement as well. So that explains the high cranking speed (no compression) but I want to know what caused the chain to fail. Kind of sucks and sorry for the long story but I was just wondering if anyone has had chain failure like this? I'm pretty sure it a non interference motor but does anyone know for sure???

Its a 87' 4.0 (RENIX model), manual tranny, the Jeep is completely stock engine wise. The Jeep has 290,000 miles and is very well taken care of. Two years ago I got a 95 motor with a blown head gasket and completely rebuilt the engine. It still has my RENIX intake and all stock components off the non HO engine. The engine was professionally rebuilt with new pistons, cam and all machine work. Also, it was rebuilt to 95 specs and all internal components used were for a 95 (nothing is miss matched mechanically from the 87 to 95 engine, just intake and supporting management stuff). Only has about 25,000 miles on rebuild. :twak:

I'll post back after I have time to tear into it and find more stuff visually. I hope the chain was just flawed and broke. Hopefully the oil pan and what not is all full of metal. One last thing, it made no noise when this happened. No bang, crack, snap or anything...

Any input???

was it an aftermarket chain? you really won't know the true cause until it is taken apart. mike

Did you replace the timing set during the rebuild?

Yeah, everything mechanical was new. Timing set, cam, oil pump, ect...

Its shouldn't have let go after only 25000 miles. I would talk to the company that made it. I have heard of the single row chains eating a crank gear, but that was on a stroker.

Might have been cam or crank gear failure also.Take it apart.

Yeah, I'll have to take it apart and look. I noticed when I got the rebuilt kit the timing chain seemed a little thinner to me. I think there is a single roller and not double roller in there right now. I wonder if thats what failed, it would seem to be the most reasonable explaination to me. But my engine is all stock and I dont rev it high to often so you'd assume if all the gaskets were correct and everything matched up then the timing chain that installed correctly must have a normal service life.

What do gaskets have to do with the timing chain?

Talyn said:

What do gaskets have to do with the timing chain?

Click to expand...

Directly? Nothing at all but I have gotten parts that are miss packaged. Assuming that box was marked correctly and all the gaskets matched up I think it probably rules out I got a miss packaged timing chain. Although you can argue that would have to be one hell of a miss package mistake so maybe its a 2.5 and not a 4.0 chain? Probably not and if it was I bet they are the same anyway. Any one ever get a timing chain and find that the new replacement one is a lot thinner then the stock one? I noticed the new one had one or two less links thickness wise, not sure if that means much either. Also anyone know for sure if the 4.0 is a interference engine or not? I want to say its not...? Anyway, hopefully tomorrow I'll have time to tear into it and I'll post up what REALLY happened or even take some pics...:doh:

It means its a single row. The timing chain shouldn't come with gaskets unless it was one of those cheap rebuilt kits.

I'm not 100% sure, but I talked to a guy that had his timing chain stretch and jump a tooth while driving. He said he could hear all the valves hitting the pistons. He didn't bother tearing it apart to see and got a new project. An indication without tearing the head off would be to check to see if you have any bent push rods

I am not sure if it is a true interference engine or not. Jumping one tooth would not cause the valves to hit the pistons. Breaking the chain or stripping a gear then trying to crank it over could cause them to kiss. The quickest and easiest way to tell if the met is to find a bore scope and stick it down each spark plug hole.

at factory deck height, it is not an interference motor. I have no idea how close the come, but I know you can turn the crank two full revolutions without a chain with no contact.

Well, I pulled the timing cover off and found this...

Got the fans and shrouding out of the way...


After pulling the cover I found this...


Closer look at all the teeth sheered off the crank sproket...


I looked at my old paper work and I'm pretty certain its a Cloyes C-3041 Timing Chain set. I can turn the cam over with a socket and ratchet fairly smoothly and it feels consistent through the valves opening and closing. Not sure why this type of failure happened. Looks like I'll be pulling the oil pan to clean it out and going to Pick N Pull to get a used timing cover. Any recommendations for timing set brands? I want something good and fits like factory. I don't need a performance one, just something legit. Has anyone ever seen a failure like this? Any other ideas on what to check or what might have happened? :doh:

I think you need to find out why your cam suddenly stopped. Did the oil pump freeze up or jam?

No bueno!! I've never heard of something like that happening.

Cloyes double roller. This is exactly what I saw before on JeepStrokers.com. He was running heavier springs, but it still shouldn't have done that in his case. And even less so in your case. I'm thinking Cloyes has some issues with their single roller timing sets.

I would also remove the rockers and see how easily the cam turns over then.

http://www.jeepstrokers.com/forum/viewtopic.php?f=5&t=1336

Its hard to well what happened. The Cam gear has about two teeth missing and it has heavy imprints on both sides of the teeth of the chain being pressing into it. I'm not sure what happened. I'm going to pull the rockers and check for bent push rods, check the top of the valve stems with a straight edge (looking for low ones aka ones stuck open) and turn the cam with out the spring pressure. I wonder if a tooth broke off the crank sprocket and caused the chain to stretch and jam up in between the cam sprocket and timing cover, with the crank still spinning it could shear all the teeth off. I'm trying to look to see if any of the breaks or surface texture of the metal looks different. Kind of like a tooth breaking off vs. a tooth shearing off.

Talyn said:

Cloyes double roller. This is exactly what I saw before on JeepStrokers.com. He was running heavier springs, but it still shouldn't have done that in his case. And even less so in your case. I'm thinking Cloyes has some issues with their single roller timing sets.

I would also remove the rockers and see how easily the cam turns over then.

http://www.jeepstrokers.com/forum/viewtopic.php?f=5&t=1336

Click to expand...

That link looks similar to what happened on mine, except mine is all stock. hmm...:eyes:

Hey guys I need some tq specs for a 95 4.0.

Cam Gear to Camshaft Bolt
Oil Pan, small and big bolts
Oil Pump
Rocker Arms to Cylinder Head
Timing Cover, small and big bolts
Valve Cover

I think thats it for now, THANKS!