98 SOHC rattle at idle

[andypalmer]

Hi all,

I have a slight rattle, only audible at idle but there regardless of engine temperature and running time. It is worse under load, in gear held on the brakes but disappears if you force the revs above around 800rpm with the throttle. At first I thought it was related to a poor idle but yesterday I was advised that it is the rear timing chain. I had the 00M12 modification done off my own back which included the plastic rod for the front chain but the rear chain has never been touched. Does anyone have any realistic comments on whether this is likely to get worse and if so, how long as I dont really want the engine blowing up but an engine out repair wouldn't be too cheap. If it is likely to remain just a noise I can live with it but I know the reputation these have.

Many thanks,

Andy.

 

[Steeda90GT]

This was discussed in another thread. A number of forum members have the timing chain rattle and still drive their trucks for many miles. Some drive for 10, 20, 50, even 100,000 miles with the noise.

What I'm trying to say is every case is different, but it seems like 99% of the time nobody had an actualy engine failure.

 

[CDW6212R]

Change the external tensioner in the right head. Everyone should do that on a 4.0 SOHC, and the front one, every 50-75k miles. Those have internal mechanical springs which weaken over time. The chain becomes loose when that happens, that makes noise.

That would be a minor noise compared to having the internal chain cassettes begin to fail. Do the external ones first, they are cheap and easy to do. The rear one should take less than 20 minutes, most for removing the right inner fender. Regards,m

 

[andypalmer]

Thanks for the response guys, that's pretty much what I was hoping to hear. The noise doesn't bother me too much but I don't really want the engine trashing itself. CDW6212R, I was under the impression that none of the rear chain can be accessed without removing the engine from the vehicle, is that wrong? If there is anything I can do (without removing the engine) that is relatively easy I'll consider it as I really want to keep this truck on the road. Is there a post or link to a guide to how to change the tensionners?

I really appreciate the responses as very few people have even seen an Explorer in the UK, let alone worked on one!

 

[CDW6212R]

The two external tensioners are half of the SOHC issues, and they are external. Change them yourself, the front(that's the TSB you read about) requires removing the upper intake and carefully getting the tensioner out and in. The right tensioner as I mentioned is a five minute job with 24" of extensions, after you have the inner fender out.

 

[andypalmer]

CDW6212R, by inner fender do you mean the wheel arch lining? We obviously call things slightly different names over here as I'm not sure which part the fender is. Sorry to be a pain!

 

[CDW6212R]

Yes, the plastic inner fender liner. It's not much fun to R&R, there are several small bolts and screws. With that out of the way, you can see the tensioner.

Below are the rear, and front tensioners. The rear part has a very thin head, it's at the top rear of the right head. They both go into the heads the same way, the heads could be swapped if necessary(they are identical). The front unit sticks out quite a bit, which is why the intake has to come off to remove it.

 

[andypalmer]

I assume the tensioner is the white plastic part with the spring behind it? If so is it fixed or held in place by the tension in the spring? My X has flared wheelarches as well, these look like they have to be removed before removing the inner fender, is this correct? Sorry to ask what may sound like basic questions but I've never had to do anything like this before.

 

[CDW6212R]

The tensioners are the black steel part, they are self contained with a spring inside. The internal spring and oil pressure are how the chains are held tight.

The white plastic is part of the large chain cassette assembly. That plastic is what is prone to falling apart in the pre-02 models. If it begins to, then the symptom shows as noise, from the chain becoming more loose. You are hoping to keep high quality oil in the engine, and that the external tensioners are weak.

Don't remove the fender flares, they are also held on with lots of plastic clips that you can't see easily. Remove any screws that you need to for the inner fender liner though, they are easy to deal with.

I have a rear tensioner here at my desk, for a forum member friend in Australia. The rear tensioner part number is 7U3Z 6K254 A, it is about as long as your middle finger.

 

[david_l_h69]

do yo have a part number on the front tensioner?

 

[RockyMtnHigh]

CDW6212R, by inner fender do you mean the wheel arch lining? We obviously call things slightly different names over here as I'm not sure which part the fender is. Sorry to be a pain!

On this side of the pond wings are fenders, bonnets are called hoods and boots are trunks.

Cheers mate!