Comanche Timing Overview?

[fronix4]

Hey guys, I'm working on my 86 2.5 L Comanche. I would like to inspect the timing sprocket/chain. Can someone please tell me if you have to remove the oil pan and water pump? It certainly looks that way. Thanks.

[MiNi Beast]

yes you do. But might as well, then replace all the gaskets and seals why you have it apart.

[fronix4]

Thanks. I figured you had to do that, just wasn't sure. That's a good idea to replace the gaskets. They leak a little anyway. Should be a fun little project!!!

[maddzz1]

Is there a certain mileage where you should replace the timing chain?

[fronix4]

On most vehicles that have a belt, I've heard that it's good to change the belt every 3 - 5 years or 80 to 100000 miles. I'm not sure about the chains. I heard that the chains usually are ok until they break, but plastic and nylon sprockets and tensioners get worn.

 

I had a non-interferance engine in my dodge shadow, the belt broke at 80 mph. I am lucky it was a non-interferance motor, so it did no damage to the engine. My dad said he had an old buick in the 60's that had a chain that broke, and it nearly ruined the motor. He changes his timing belts/chains about every 60000 miles so he's never stranded. He is anal though. He has a 50 year old car that has 400 000+ miles on it, and never broke down. He's like Hank Hill.

 

My Jeep has 223 000 miles, and is only on its second chain, which I suspect is what is wrong with it. I should've listened to my anal father.

 

I guess better safe than sorry, right?

 

I hope someone more qualified can answer this for us all. I have heard a lot, but am unsure of how valid it is.

 

I would like to know what a auto repair specialist would have to say. I just wanted to add to your post, so maybe some mechanic will have a better answer for us.

[Eagle]

The chain itself is good for at least 200,000 miles, probably more. The issue with the 2.5 liter is that Jeep used the same timing chain they used on the 4.0L, but the deck height on the 4-cylinder engine is lower. That left slack in the chain, so they put a tensioner on the timing chain cover, and the tensioner wears out. Once you get the front cover off, you may find that you don't need a timing chain at all, just the tensioner.

 

However, once you're in there, timing chains aren't expensive, so it would make sense to replace it.

[mjeff87]

you do not need to remove the oil pan nor the water pump to remove the timing chain cover on either the 2.5 or the 4.0

 

Like Eagle said, the chains are good, but the tensioner fails on the 2.5. Mine went bad around 150K (made a clacking sound that I drove with for another 20K miles with no performance issues). I opened it up around 170K and replaced the tensioner as well as the chain and sprockets while I had it all torn down.

 

Jeff

 

edit: here's the writeup I did so you can see what's all involved....

 

http://www.comancheclub.com/forums/view ... ming+chain

[fronix4]

Excellent info guys. Thanks to all.

 

It makes sense that the sprocket/tensioners go bad. Don't see a chain stretching, and hard to snap with a little 2.5 L.

 

 

So, if I need to inspect the chain, what would you remove first from a 2.5 L? It looks like it's past the water pump, and I haven't seen any easy access panels like on some vehicles. If I wanted to get down to the chain, where do you begin on the 2.5 L? Valve cover? I don't have a place on the block to view the timing, but have the notch on the bell. The notch is off from the arrow, so I think the tensioner or sprocket is bad.

 

 

Man, please keep helping, you guys are awsome! I hope I can help you guys sometime. This site is one of the best ideas for people like us, who like to learn and grow and share knowledge. I am learning a lot from you guys.

 

 

 

Thanks sooo much!!

[fronix4]

Thanks Eagle and MJeff87 for the last two posts. I'm going to follow your link to the writeup. It will probably answer my last post....thanks.

[fronix4]

Sweet Mjeff87, your posted write up is EXACTLY what I needed! Nice pics and data. Most appreciated.