Puff of blue smoke on WOT shift

[Hagan]

I noticed today that when I shift at WOT I get a big puff of blue smoke out the exhaust. It's usually after I shift and when I go WOT again. Any ideas what could be causing it?

I'm hoping it's something to do with the heads. But not sure how I can diagnose where it's coming from?

 

[Mark_88]

Sounds like valves or valve seals.

You can do a compression test/leak down test to see if you have a leaky valve on any cylinder or wonky rings. Watch more closely on all shifts to see if it is puffing when you let off the gas...its basically oil getting sucked past the rings or valve seals.

Another thing you can test is open the hood before you start the truck and then remove the rubber tube from the valve cover vent. There should be very little or no mist from that even on coldest days...but if you see mist after a few minutes on a warm day then it may indicate blow by....or other problems...

 

[Hagan]

Thanks Mark. I've used the blow-by test on many used vehicles I've purchased throughout the years. I've seen some very bad blow by. Surprisingly this engine was rebuilt (has a warranty tag on one of the freeze plugs) and was in great condition. Did a compression test all cylinders were above 170 psi and consistent. I bought it off craigslist for $50.

The only thing that was missing was the pushrods. I somehow measured them (forgot how). I swapped from a flat tappet cam to a very disappointing roller cam from a 302 block I had laying around. Every day I get a tick (sometimes loud) from one of the HLA's. The only issues I've had with the engine is a cutting out issue above 4k rpm. It kind of surges. Some slight oil leaks. And I am getting some white foam crap on the bottom of the dipstick. Not sure if that's because I have poor ventilation?

If it's the heads I want to upgrade to aluminum heads and a different cam. I'm very disappointed in the power of a 302 in my Ranger.

 

[Mark_88]

LOL...for some reason I was picturing this as a 4 banger. The same applies to a double 4 banger but things just moved around a bit...

$50 for a 302 is a good deal so you probably have gotten your money out of it by this point.

Have you added any oil conditioners like Lucas Oil or other? The foam can be a by-product of some of the ingredients in the oil and Lucas Oil is notorious for foaming.

Not likely a PCV issue but it wouldn't hurt to swap in another one if they are inexpensive. I just dislike swapping in parts if they are not needed. The rattle test is not a good indication of function on those but you can hook up a vacuum source and see if the valve closes with vacuum.

 

[enjr44]

When you come off the throttle at high rpm you get super high vacuum (engine spinning; but, can't get air). So the engine is sucking from every place. After you change the PCV, the valve guide seals would be my choice only because you can change them without pulling the heads.

 

[85_Ranger4x4]

Cold engines that are not allowed to run at operating temp for longer periods of time will create a snotty substance on the oil fill cap and maybe at the top of the dipstick... condensation from a warm engine cooling down in a cold enviroment. They need ran for some time to get the moisture evaporated out.

Bottom of the dipstick, like the part that is supposed to be in oil?

What cam did you put in?

 

[Hagan]

Have you added any oil conditioners like Lucas Oil or other? The foam can be a by-product of some of the ingredients in the oil and Lucas Oil is notorious for foaming.

Not likely a PCV issue but it wouldn't hurt to swap in another one if they are inexpensive. I just dislike swapping in parts if they are not needed. The rattle test is not a good indication of function on those but you can hook up a vacuum source and see if the valve closes with vacuum.

Nope no oil additives. Just 6 quarts of 10w-30. The PCV is newer (4 months old?) But I'll have to look into and make sure it's working. I was pulling a lot of vacuum when the engine was running. I believe I had around 20.

When you come off the throttle at high rpm you get super high vacuum (engine spinning; but, can't get air). So the engine is sucking from every place. After you change the PCV, the valve guide seals would be my choice only because you can change them without pulling the heads.

I will have to investigate this. If I pull the heads I'm going to put on aluminum heads.

Cold engines that are not allowed to run at operating temp for longer periods of time will create a snotty substance on the oil fill cap and maybe at the top of the dipstick... condensation from a warm engine cooling down in a cold enviroment. They need ran for some time to get the moisture evaporated out.

Bottom of the dipstick, like the part that is supposed to be in oil?

What cam did you put in?

I admit, the furthest I've driven this truck is 9 miles to work. 3 days ago I did a 120 mile trip in the snow. The next day I did another 60 mile trip. After that I noticed the smoke. It's never ever smoked in any situation. Never on startup, never on wot shifts, never at 6k rpm, until 2 days ago.

Yeah the very tip of the dipstick in the oil has white foam on it. My brother has been telling me it's due to lack of ventilation.

The cam came from a 302 roller block. I bought the block 3 years ago off craigslist. It's a non-HO roller cam. I didn't even know they exsisted until I couldn't figure out why my firing order was for a non-HO block.

 

[85_Ranger4x4]

Not really ventallation per say, just needs heat. Normal for new stock engines to do it too.

Non HO cam is good for torque, HO is good for racing.

Mine started out with a non HO cam, torque off idle was brutal but it started pettering out around 4k. Rated like 286lb-ft or so around 2500rpm.

Everyone said they are gutless, HO is much better... so I switched and now I don't have near as much down low and it starts to wake up around 4k.

Needless to say I regret that "upgrade" since I rarely rev it that high in normal driving.

 

[Hagan]

Not really ventallation per say, just needs heat. Normal for new stock engines to do it too.

Non HO cam is good for torque, HO is good for racing.

Mine started out with a non HO cam, torque off idle was brutal but it started pettering out around 4k. Rated like 286lb-ft or so around 2500rpm.

Everyone said they are gutless, HO is much better... so I switched and now I don't have near as much down low and it starts to wake up around 4k.

Needless to say I regret that "upgrade" since I rarely rev it that high in normal driving.

I do feel like my 302 has good torque off idle just nothing on top. I swapped to a HO 302 in my '92 Bronco I just sold and it pulled hard at 4-5k rpm.

Maybe I'll change the oil and start driving the Ranger more. I've been idling it in the morning before work.

I've never had this issue on any of my vehicles. I never drive far. But I feel like 9 miles it should be hot.

 

[85_Ranger4x4]

Its hot, but not hot long enough.

I have had all mine do it when I just do short drives. If I go to Omaha (hour drive) it is gone.

It has to be hot and hot for awhile to clear the stuff out.