Pulled heads off, Lean, help...(PICTURES) | Ford Explorer Forums - Serious Explorations

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Pulled heads off, Lean, help...(PICTURES)


Well-Known Member
April 11, 2007
Reaction score
City, State
Chesterfield, MI
Year, Model & Trim Level
98 mountaineer v8
BACKGROUND INFO: My 98mountaineer v8 has 254K miles on it, runs strong but needed something...tmh's and intake spacer. So in prep for that, i decided to pull some things off to do some checking....

First I had a set of old crown vic heads my buddy just rebuilt so i had something to compare them to.. I've been smashing my head into the fender trying to figure out why its running so lean..I've never thrown a code either.
My gt40p's are on the right, crown vic's on the left


Here is a list of mod's i've done, i've tried to see if anything i've done might have caused it, but have yeilded no results.

1.7 rockers, Cold air intake, cat back, modified the mass airflow housing a touch.... Nothing over and above what i should be able do without it being so drastic..

On another note I noticed the upper to lower intake gasket was wet on the back half with fuel. (I was thinking the valves were somewhat floating and letting some air/fuel mixture run back to the intake.

I have new, stronger valve springs i'm installing as well as a valve job on the head as the exhaust valves are pretty well shot. Heres some pictures




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coul have been a comination of things-like a vacuum leak, and the intake working together to deliver too much air-
You might catch it with new gaskets-
I'd do fuel filter-and check fuel pressure when you rebuild.

Definitely get an xcal and maybe even a wideband to monitor this-

At 254k you should be rebuilding the engine not just doing a valve job. IMHO freshening up the heads to put on a 254k engine is a bad idea.

Yeah, I agree. For a few extra hours of work and a couple hundred dollars you'll have a fresh engine to stick back in. The bottom ends of 5.0's are strong, but everything wears and weakens eventually.

Besides, it's fun to rebuild an engine...

Well here's the deal with the low end... My plan was to use uncle sam's rebate check this summer to help swap in a 347 as this summer it won't be a daily driver anymore. The cylinder walls still have cross hatching and there is NO lip at the top of the cylinder walls. At 254k miles it burned no oil, leaked no oil, ran pretty strong.

When i talked to bob pasquale he was saying how poor the stock manifolds were and as things begin to leak a bit (the exhaust valves), the engine basicly eats its own exhaust..

I really don't want to pull the low end at this point, it looks more than capable of running another 6 months with no problem, and i plan on using the current heads with the 347 block. And the cash flow right now doesn't really support this idea either.

With the addition of new headers, I don't want to blow the motor running it so lean. I had it narrow'd down to the fuel pump not supporting the fuel demands wether it be bad, or just maxed out as i read the fuel pump is also the same one used in the 4.0l. Mr. Jsmith i know you have that awesome 347, was fuel an issue for you as well? Intake leak was another option, but without throwing a code, fairly smooth idle/performance, and a pretty careful install last time i took the intake off, points to something else. I did modify the mass airflow housing and after careful tweaking i got it to stop throwing codes. So i was going to swap it back to a stock housing. I just don't understand why the o2 sensors arn't compensating for this lean condition as they are all new. I'm buying a bama chips programmer as soon as i get the headers done as well.

Thanks for all the info/help.

I was told that a hooking up a fuel pressure gauge won't give you accurate results unless its in the high r's and under a load.. true ??

btw i did change the fuel filter less than 3k ago, and usually change them every 10-15k.

Why put money into something you're gonna scrap in 6 months?
The reason it was running lean was probaily cause you din't have it tuned up for the new stuff and your fuel pump and injectors were probaily worn and tired. mine ran lean with those mods too till i got it tuned.
Cylinders are kinda one of those things that don't go bad as fast as something like bearings, and main seals. put more strain on the old engine parts - spin a bearing - throw a rod - blow a main seal - ect

When I did my engine mod thing-
I switched to:

255 lph fuel pump
aeromotive rails
aeromotive adjustable regulator
42lb injectors.
I did have a lean burn happen once back in 2004-but it was induced by me I think, while trying to dial in a maf sensor.

Did you have a chip, or programmer on there?

also-just for giggles--

check the crank pulley
better yet-
get 3 pics for me
back side-
front, and side view
I want to see the marks and keyway please.

are you talking about the balancer marks/keyway?

And i'm not really putting the money into something i'm scrapping in 6months, i'm trying to keep the money going to things i'll keep. I plan on building a short block on a stand and swapping it out reusing the gt40p heads and oil pan.

Bob said my headers will be here wednesday, so i plan on having everything back together and running friday. Then i have to buy a programmer and i'll probably swap out the fuel pump to a 255lph, (ebay 60$) I've done the reading, Is a bama chips tune the way to go?

I'm going to check and double check to make sure the intake's are sealed good and that there is no chance of leaks.

are you talking about the balancer marks/keyway?

Is a bama chips tune the way to go?
Yes to the marks and keyway-

I wanna see something-

No to the bamachips question

talk to jah81592 for your tuning-he is the site vendor for this type of thing


A 255lph pump is overkill for stock injectors. Wait to put it in until you put the 347 in.

could be you just floor it a lot and those are just deposits

White on the valves is to be of a little concern, but I would suspect you really weren't that lean. Although I could be wrong, the only true way to tell is to put a wideband on your application and datalog with a few pulls. I have seen white on the exhaust valves on stock applications without a mod performed. As far as your application, you definately need tuning.-j

I have some pictures of the crank pulley, my camera's about ready for the trash, and with the motor still in the truck, it's tough to get a good picture Hope this is what you wanted. Sorry the lower end of the block is pretty nasty with all the coolant that came out of the heads/intake

I basicly havn't left the garage in like 3 days. Work basicly slows to a crawl in the winter so i have time to waste on this.




My heads are going to be done tomorrow morning, i have to assemble them, my tmh's are coming tomorrow as well so i'll be just about all set. Everythings all painted up ready to go. Thanks for the help with the programmer (jtsmith and jah81592) I'm giving them a call tomorrow and see what i can get.




Your intake looks nice-:thumbsup:

Thanks for the crank pulley pics-
but this is for you not me
I want to see the KEYWAY area

in other words-pull it off-take a picture please of the keyway.
draw a line if you can from the keyway knotch to the white timing mark-I'll betcha they don't line up anymore!!!!
This will cause an error in ignition timing sure as spit. The computer uses the trigger sprocket position to determine timing-
but the crankshaft position will actually be off by few degrees.

Now, the reason it shifts is because it is a 3 piece design-held by a rubber inner sleeve that is wedged in tight.

Well i understand what you mean now. With the outer having the chance to spin on the inner part. I talked to my buddy who put a 302 in a bronco2 and he had to get a new balancer because the rubber dry rotted out and spun on his balancer. I'm going to pull the pulley off and take a look, see if i can see any spinning/dry rotting. I'll post some pic's of the keyway w/the pulley off. Thanks again.

Sorry for taking so long. well the headers are in, heads are on, intake's on, all done, running. I didn't have a puller to get that balancer/pulley assy. off but with the valve covers off i put piston 1 to tdc and looked at the pulley and it did read 0...So all is good i assume?