Blue smoke on newer rebuild

ILOVEFASTCARS

MEMBER
1993 FORD RANGER
4.0L
V6
4WD
MANUAL
33,000 MILES

My truck listed above XLT model has about 33,000 on a rebuild (lifters, pushrods, rockers were not replaced).

It was not smoking when I bought it from my dad who did the rebuild. I drove it home 1,500 miles and now it's smoking blue when the engine is warm. I can see it when I'm at a light, rather embarrassing!
I drove it cold (65 degrees out) around the block today (once) and it didn't smoke at all yet had a smelly exhaust, not an egg smell. I did notice a little condensation in the tail pipe. I live in Phoenix so this seems odd to me but it is a cooler day.

One person tells me rings, but dad replaced them and new pistons, internet searches says valve guides/seals. The engine doesn't act weird, always starts and turns off fine. No rough idle, seems to run fine, just smokes and burns some oil. I don't notice smoke when it first starts. A friend driving behind me says it smells and smokes.

I replaced the 6 plugs and no oil was on any of them and they looked rather good. I also replaced the PCV. There is no steam or strong pressure coming from the PCV hose and it's not oily inside the hose. The truck does die when it's running and I remove the PCV hose to look for steam or pressure yet I assume this is normal.

Thoughts?

4 Replies

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

Hi,

If it's blue, it is certainly oil. Since it runs normal and starts easily, I don't feel it is an excessive fuel issue causing cylinder wall wash.

What I am going to suggest is this. We need to do a compression test two ways. First, you are going to do is "dry." In other words, simply remove the plugs and check compression. The second time you are going to do a wet test. In this case, you will add approximately a tablespoon of motor oil into the cylinder via the spark plug hole and then do a compression test. If there is a substantial difference between the two test, then we have a ring issue. If there is little to no change, it's likely the valve seals.

Also, by testing compression, we can see if there are any variations from cylinder to cylinder indicating a possible head gasket issue.

Here is a link that explains how to perform a compression test:

https://www.2carpros.com/articles/how-to-test-engine-compression

Also, take a look through this link and let me know if anything helps:

https://www.2carpros.com/articles/blue-smoke-from-engines-exhaust#: :text=When%20a%20car%20is%20producing,along%20with%20the%20normal%20gasoline.&text=A%20blue%20smoke%20condition%20is,sitting%20for%20a%20few%20hours.

When checking compression, there shouldn't be more than a 25% variation between the lowest and highest cylinder, so keep that in mind.

One last link. If you find an excessive variation in compression, take a look through this link and follow the steps:

https://www.2carpros.com/articles/head-gasket-blown-test

Let me know what you find or if you have other questions.

Take care,

Joe