1999 ford explorer with lots of miles questions

[Bootless]

So my 4.0 has 311000 miles im wondering if there will be anything internal i need to worry about like rods lifters rockers or anything else any input will help

 

[mark2016]

So my 4.0 has 311000 miles im wondering if there will be anything internal i need to worry about like rods lifters rockers or anything else any input will help

Lot of miles, how was the maintenance on it over its life? How does it run now? Any codes? Have you ever looked at live data and fuel trims to tell anything about how it's running? Ever had a compression test? How are the timing chain tensioners, were they replaced about every 70K or so?

 

[Bootless]

Idk just bought it a few months ago looks like good maintenance just put new transmission in it it throws codes for two lean

 

[mark2016]

Idk just bought it a few months ago looks like good maintenance just put new transmission in it

I'd suggest change the oil and filter, and run for codes then. If nothing pops up drive it and enjoy it. You can't change the history of the engine now, however to get it to that mileage it must have had some decent level of care.

 

[ranger7ltr]

I might as well ask...

Which engine is in your 99 Explorer???There are 3 possibles from the factory;
4.0 OHV, 4.0 SOHC, & 5.0 Liter V8...

 

[deadernie]

Which engine is in your 99 Explorer???There are 3 possibles from the factory;
4.0 OHV, 4.0 SOHC, & 5.0 Liter V8...

Well we can narrow it down to one of the two V6 possibilities.

 

[1997XLTRollover]

Well we can narrow it down to one of the two V6 possibilities.

And based on his info it's a 94 so it's the OHV. Process of elimination guys. lol

 

[mark2016]

And based on his info it's a 94 so it's the OHV. Process of elimination guys. lol

Says 1999 in the header.

 

[1997XLTRollover]

Says 1999 in the header.

I just saw that lol. :bdrunk:

I'm going with 4.0 OHV or the 4.0 SOHC was replaced 5 times already haha.

 

[mark2016]

I just saw that lol. :bdrunk: I'm going with 4.0 OHV or the 4.0 SOHC was replaced 5 times already haha.

I'm impressed if it's a 4.0 sohc with that mileage. Must have had really good maintenance and granny driven by previous owner.

 

[Bootless]

Ohv

 

[Dr Mordekaiser]

Holly cow 300,000+ that's incredible. My 99 v8 only has 98,000. I hope to get to run it forever!!! Time to do a maintenance check

 

[Bootless]

It gives a lot of attitude I the mornings trying to start it but other than that it rings good

 

[koda2000]

I'd just do regular maintenance and drive it gently. Not much point in tearing into an engine with 311,000 miles on it if it isn't demonstrating a problem. Even if it is showing it's age you're not going to significantly lengthen its life span. Sooner or later something major is going to let go it and it probably wont be worth fixing. I'd say maintain it normally and drive it until it blows up or the transmission lets go. Who knows, you might get another 100K out of it. Obviously the production tolerances were in this truck's favor, but none of them live forever.

BTW. Whatever you do do not flush the transmission. I wouldn't even change the filter with 311K on it. Flushing the trans would probably kill it for sure.

 

[delexploder]

Rockers and pushrods are shot I guarantee , probably the cause of your code , I have seen it on several ohv 4.0s with that kind of mileage, good news is the ones I have seen got new pushrods and rockers and are still running but like new, tough little motor

 

[Bootless]

I'd just do regular maintenance and drive it gently. Not much point in tearing into an engine with 311,000 miles on it if it isn't demonstrating a problem. Even if it is showing it's age you're not going to significantly lengthen its life span. Sooner or later something major is going to let go it and it probably wont be worth fixing. I'd say maintain it normally and drive it until it blows up or the transmission lets go. Who knows, you might get another 100K out of it. Obviously the production tolerances were in this truck's favor, but none of them live forever.

BTW. Whatever you do do not flush the transmission. I wouldn't even change the filter with 311K on it. Flushing the trans would probably kill it for sure.

I did change the fluid and filter now it has new tranny in it

 

[colintrax]

Smoke the intake to look for intake gasket leaks. I bet you have one. Driving the truck with lean codes is shortening it's life. If it runs good otherwise, keep up on oil changes and just keep driving it. Might be good for another 300,000. Never know.

 

[Bootless]

Smoke the intake to look for intake gasket leaks. I bet you have one. Driving the truck with lean codes is shortening it's life. If it runs good otherwise, keep up on oil changes and just keep driving it. Might be good for another 300,000. Never know.

How do i do that

 

[colintrax]

How do i do that

You can search on here, or use google. But basically you fill a pint sized paint can with mineral oil. Drill and tap the lid for a glow plug from a diesel truck, a male plug for an air compressor, and afix whatever line you want for the outlet. I used some old fuel line.
Hook the the glow plug to a battery charger at 2 amps or so. And set the air compressor to <10psi. Put the outlet hose somewhere in the intake. You need it sealed off though for obvious reasons. Now look for smoke leaking out. Total cost is about $25 assuming you own a battery charger and air compressor.

If you dont, there's other ways to look for a vacuum leak. Spraying carb cleaner while the truck is running is a good way. It'll mess up the idle when you spray the leak.
If you smoke cigars, blow the smoke into the engine bay with the truck running. However for the technique to work, you need to remove the fan.

The 4.0 OHV leaks at the upper and lower intake manifold more often than not. If you end up having to replace those gaskets, I'd suggest you replace the fuel injector o rings while you're there.

 

[Flash]

I'm impressed if it's a 4.0 sohc with that mileage. Must have had really good maintenance and granny driven by previous owner.

I had a head off my SOHC at 275000 kms, it showed no discernible bore wear.
I replaced the timing chains, guides, tensioners at that time.
It's at about 300 K kms now and it purrs like kitten ('til the lake pipes roar)

I see no reason why I shouldn't do 300k miles.