Difference between the years for the SOHC

[hunterzach_02]

First off, I tried using the search to find the answer but I came up with nothing after an hour.

So my dilemma is I need a new engine for a 1999 Explorer Sport with the 4.0 SOHC. I have a lot of top end noise when trying to start it but it only starts after its set for a while. Then is only for about 5 seconds. So I am assuming at this point the noise is the valves and pistons doing a mating call.

I looked up some replacement engines and the only returns I got using car-parts.com was for 1999 explorers and mountaineers. I was wondering why I couldn't use a SOHC from another year? Any insight would be great. Thanks ahead of time.

 

[Glen4X4]

It could just be the tensioner or guides or both that is doing the rattling, if you're going to go through the trouble of taking the engine out then I would take it out and check it out and see if its those that need replaced because then you know what you have. If you go with a junkyard motor then it could develop the same issue after awhile. But you can use a 98-01 but with a 98 you have to swap the fuel rail. I'm pretty sure you can use 02+ but not sure what all changes were made to those if any.

 

[2000StreetRod]

SOHC V6 replacement engines

Engine differences

The intake and exhaust manifolds differ from yours on the later models. If the rattle only lasts for a few seconds after engine cold start I doubt it is a piston/valve interference problem. That noise would not subside. My guess is timing chain slap due to a broken guide assembly. I believe the 2002 and later engines have the improved guide assemblies and primary tensioner. Guide assembly failure can happen as early as 45,000 miles. If you have the time, tools and skill I suggest that you determine what's wrong before pulling and replacing the engine. Removing the valve covers would probably reveal the souce of the noise.

 

[hunterzach_02]

Thanks for all the quick replies. The engine itself will only run for about 5 seconds so I don't know how long the noise actually lasts. I haven't had a chance to check the timing to be sure its out of time yet. It does make an odd clicking sound as it turns over from the starter. I do know it has been sitting for about 6 months.