4.0 w/180,000 miles rebuild advice....

[mjonesjr]

I am getting a 4.0 from a local guy that has 180,000 miles. He says that it has a slight oil leak, a little knock, and smokes a bit.

Any advice to rebuilding it? What should be replaced and what will be fine? If the pistons look bad, then I will replace them, but if they look fine they will stay (unless otherwise recommended). I want a stock rebuild, the stock 4.0 has plenty of power for a Bronco II.

 

[Giant squid]

if i lived in america i would just buy a remanned engine they seem to be dirt cheap from what ive seen, (im in alberta). ive seen ads for reman's around 1900$ and the cheapest i can find locally is around 3000+800 core.

 

[mjonesjr]

$1900 is cheap?

I can get the engine and EVERYTHING under the hood or anything else I want off the truck for less than $100. If I spend $900 on a major rebuild kit, that is $900 saved for a rebuilt engine that I did myself.

 

[MAKG]

Inspect it and replace or repair what is out of spec.

That's how you rebuild an engine. You don't install a kit.

It's also how you keep from getting screwed by "cheap" rebuilders.

On a known-smoker, I'd replace piston rings and consider valve guides. But do you need to bore the block? By how much? That affects which rings you buy. Same deal for bearings. Is the crank straight and true? How about the rods? Are the pistons flattened? They may or may not need replacing if the block isn't bored.

Valve guides should be replaced if clearance is excessive. Valve SEATS should be replaced if excessively recessed (almost always on the exhaust side). And so on.

 

[AllanD]

I can get RUNNING 4.0 engines in essentially unlimited supply for $175-$250.

I have stated many times (but will do so again here & now for anyone that's missed it)
That "rebuilding" a 4.0 (or a 2.9) is an act of either insanity or stupidity (and likely both)

Why? Why do I consider lotteries a tax on people who are bad at math?

If I can get a running engine for about what a complete engine gasket set with headbolts typically costs, it makes far more sense to "yank and replace"
than "overhaul".

$1800 for an engine? No.

For $1800 I could buy two or three running 4.0 donor vehicles.

AD

 

[Giant squid]

Thats sweet. But do understand that we hear in canada dont have 10million 4.0L's waiting in line to be your next donor. I cant even buy 98tm heads without haveing them shipped from the US or ontario. But at the same time i bite my tounge remembering that you do. You guys are so fukin lucky to live the lives you do. Everything costs allmost half as much, you guys are hardly taxed, and you force other countries to sell you cheap oil, including ours. Where do i sign up!!!!!!!!

 

[mjonesjr]

Inspect it and replace or repair what is out of spec.

That's how you rebuild an engine. You don't install a kit.

It's also how you keep from getting screwed by "cheap" rebuilders.

On a known-smoker, I'd replace piston rings and consider valve guides. But do you need to bore the block? By how much? That affects which rings you buy. Same deal for bearings. Is the crank straight and true? How about the rods? Are the pistons flattened? They may or may not need replacing if the block isn't bored.

Valve guides should be replaced if clearance is excessive. Valve SEATS should be replaced if excessively recessed (almost always on the exhaust side). And so on.

Thanks. I planned on replacing the rings now matter what since it smoked. I don't plan on boring the block.

 

[Bob Ayers]

Thanks. I planned on replacing the rings now matter what since it smoked. I don't plan on boring the block.

Not very smart, the cylinders wear, just like the rings!!!

Do you know anything about checking bearing clearances (rods, mains, cam), inspecting the heads for cracks, etc.?

With your level of technical expertice, I suggest you take AllanD's advice!!!

 

[Jspafford]

Not very smart, the cylinders wear, just like the rings!!!

Do you know anything about checking bearing clearances (rods, mains, cam), inspecting the heads for cracks, etc.?

With your level of technical expertice, I suggest you take AllanD's advice!!!

Sounds like your trying to get another argument started....

 

[Bob Ayers]

Sounds like your trying to get another argument started....

I think that this statement from AllanD says it all:

That "rebuilding" a 4.0 (or a 2.9) is an act of either insanity or stupidity (and likely both)

 

[CopyKat]

look up "eristicgaskets" on e-bay. I got my head gasket and head bolt set from them and it was a reasonable price.

Nothing wrong with going through the engine and replacing gaskets. Smoking dosen't really mean that the rings are gone. But you can check them and mic the jugs to see what they are at. They may just need a hone.

 

[Bob Ayers]

look up "eristicgaskets" on e-bay. I got my head gasket and head bolt set from them and it was a reasonable price.

Nothing wrong with going through the engine and replacing gaskets. Smoking dosen't really mean that the rings are gone. But you can check them and mic the jugs to see what they are at. They may just need a hone.

The 2 main sources of oil smoke are worn rings/cylinders, and intake valve guides and seals. And a "little knock" is probably due to bearings. So, just
replacing gaskets, and honing the cylinders won't fix these problems.....

 

[CopyKat]

So, just
replacing gaskets, and honing the cylinders won't fix these problems.....

I didn't say it would.

 

[MAKG]

Thanks. I planned on replacing the rings now matter what since it smoked. I don't plan on boring the block.

If you make that decision based on desire rather than need, you're wasting time, money, and bandwidth.

If you haven't been INSIDE the block with a bore gauge or inside mic or whatever, you don't know what you NEED. How bad is the taper?

But Allan's right. Used running engines at this vintage are extremely common and relatively cheap. And if it's got a knock at 180K, it's been abused (or not kept up with maintenance and repair).

 

[eric17]

If you make that decision based on desire rather than need, you're wasting time, money, and bandwidth.

If you haven't been INSIDE the block with a bore gauge or inside mic or whatever, you don't know what you NEED. How bad is the taper?

But Allan's right. Used running engines at this vintage are extremely common and relatively cheap. And if it's got a knock at 180K, it's been abused (or not kept up with maintenance and repair).

i cant agree with you more, i have 263k on mine and no knock or smoke, rear main dips a bit here and there and the lifters tick.