Timing Chain

I have 208,000 miles on my 88 4.0 litre. Should I be worried about changing the timing chain? It runs great, it's just something I've been concerned about lately. Thanks

You sound like me. A couple of years ago my '88 hit 204,000 miles and I started to worry about the timing chain. I was accustomed to AMC V-8s, which used nylon teeth on the cam sprocket, and those would wear down and let it jump time.

So I bought a timing chain and new sprockets. The replacements were all steel gears, and the chain was a roller style, not the flat style I was expecting. Hmmm ...

Opened up the engine, and the old chain was so tight you couldn't really see any difference between it and the new one. I threw the new stuff in because I wasn't doing all that work fior nothing, but I saved the old parts and would not hesitate to use them in a beater engine.

The factory manual allows 1/2 inch of play in the chain, which seems like a lot but with all steel gears it isn't likely to jump a tooth. If you have been reasonably consistent about oil changes, I don't think you need to worry.

I do change my oil regularly. Thanks for the advice Eagle.

Danwa said:

I have 208,000 miles on my 88 4.0 litre. Should I be worried about changing the timing chain? It runs great, it's just something I've been concerned about lately. Thanks

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Unless you can hear it rattling when accelerating from very low rpm, there's no reason to worry. The 4.0 engine is blessed with a high quality chain and steel sprockets that last at least as long as the engine itself. It's nice not to have to replace a timing belt every 60k miles or worry about it breaking like you do on most modern engines.

Thanks for all the advice everyone. I think I'll take my chances for awhile.

I dont mean to steal a thread, but I have the same concern. I have 232K on mine and just bought it, so I dont know the history. I wanted to know if besides the timing chain, is there anything else that is known to be the final blow to the 4.0L? oil pump, water pump, etc.,

The water pump won't be the final blow unless you don't spot the coolant temp. gauge heading skywards but if the oil pump suddenly lets go on you and the oil pressure drops to zero, you'd better be ready to shut down the engine right away before it's severely damaged.
Timing chains rarely if ever break. They usually stretch after some time and begin to rattle either because they're overstretched or the tensioner has worn down. If it rattles a lot, it could jump a tooth (or a few) and either throw off the valve timing or worse, cause the pistons to hit the open valves.

I don't think the stock 4.0 is an interference engine.....I think that if the chain broke you would just coast to a stop from it not running...A stroker is probably different if the head was shaved and taller pistons were used upping the compression ratio.

RichP said:

I don't think the stock 4.0 is an interference engine.....I think that if the chain broke you would just coast to a stop from it not running...A stroker is probably different if the head was shaved and taller pistons were used upping the compression ratio.

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...or you fitted a cam with higher valve lifts.