Bad oil leak on front of engine

[Chuck E]

My son has a 2000 explorer with 92,000 miles on it and he noticed a bad oil leak under the truck and after thinking it was from oil pressure switch, we changed it and then noticed it was not the problem. We found a t30 bolt with a o ring wedged behind the pump and could see where it had fallen out from and put it back in the hole, tightened it up and the leak has stopped.My question is how could such a bolt just fall out and what was it used for. The truck runs fine and never had any problems when the bolt was out, except for the oil leak.

I found a picture on another thread that shows the bolt we found, any information would be appreciated.

 

[shadowless127]

perhaps it was never torqued down after previous engine work, or if came loose due to excessive front end vibration.

Those would be my 2 guesses.

 

[2000StreetRod]

cassette mounting bolt

That engine sure does look familiar! The Torx bolt you're referring is the upper mounting bolt for the left cassette guide assembly. When I replaced my cassette I reused the old mounting bolt but I applied gasket sealer to the O ring before installation to keep it from leaking. Apparently, the bolt was not torqued to specification when previous work was performed - possibly a cassette replacement.

 

[Chuck E]

perhaps it was never torqued down after previous engine work, or if came loose due to excessive front end vibration.

Those would be my 2 guesses.

Engine is original and we are original owners, no work ever done on it except for tune ups. Do they vibrate loose often?

That engine sure does look familiar! The Torx bolt you're referring is the upper mounting bolt for the left cassette guide assembly. When I replaced my cassette I reused the old mounting bolt but I applied gasket sealer to the O ring before installation to keep it from leaking. Apparently, the bolt was not torqued to specification when previous work was performed - possibly a cassette replacement.

I assume I used your picture, That thread was very interesting to read. you say it is a mounting bolt for a cassette guide assembly, was it ok to just put it back in or is there a part loose in the engine since he drove it for about 3 weeks with it out. He noticed the leak started about 3 weeks before we found the bolt. The truck ran fine and still runs good, what damage could have been done while it was out?

 

[2000StreetRod]

bolt function

Engine is original and we are original owners, no work ever done on it except for tune ups. Do they vibrate loose often?

It's possible but yours would be the first one I've heard of.

. . . you say it is a mounting bolt for a cassette guide assembly, was it ok to just put it back in or is there a part loose in the engine since he drove it for about 3 weeks with it out. He noticed the leak started about 3 weeks before we found the bolt. The truck ran fine and still runs good, what damage could have been done while it was out?

The left guide assembly is shown below.

The bolt goes in the hole at the upper end of the right section in the photo. It keeps that section from moving. The hydraulic/spring tensioner presses against the section on the left to keep tension on the chain. Since the section on the left is fairly straight and kept in position by the chain it was probably in the correct position when the bolt was screwed back in. I doubt the guide was damaged.

 

[Chuck E]

It's possible but yours would be the first one I've heard of.



The left guide assembly is shown below.
View attachment 68399
The bolt goes in the hole at the upper end of the right section in the photo. It keeps that section from moving. The hydraulic/spring tensioner presses against the section on the left to keep tension on the chain. Since the section on the left is fairly straight and kept in position by the chain it was probably in the correct position when the bolt was screwed back in. I doubt the guide was damaged.

Thanks for the information. Do you think we should take the bolt back out and change the O ring or apply gasket sealer just to be safe?

How much should the bolt be torqued?