Stumped on oil leak

I'm feeling really stupid.

I cannot figure out this oil leak. I just did an oil change yesterday and put the UV dye in took it for a short test drive today < 1Mile and I had oil smoke particularly under acceleration from oil on the headers.

The UV dye seems to indicate that I've got oil coming out of the oil dipstick. but the dipstick is still seated in the tube after driving the truck. The oil is getting onto the frame rail somehow and running down it.



Then there seems to be another leak that dripping onto the front crossmember. that may be the timing cover but I've done that seal recently.



Does anyone have any ideas?

Excessive blow by? Do you know how to check?

Could try swapping out the dipstick with a vacuum port plug and hose clamp, could just be a bad dipstick seal plus a blow by issue. Maybe pinholes in the tube?

squaredeal91 said:

Excessive blow by? Do you know how to check?

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I do not. Not sure I understand what it is either.

Rickf said:

Could try swapping out the dipstick with a vacuum port plug and hose clamp, could just be a bad dipstick seal plus a blow by issue. Maybe pinholes in the tube?

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I also thought of this. I may try taking the dipstick out and slipping some rubber hose over the end by the oil pan and then putting two hose clamps on it one on the pan and one on the tube.

Is it weeping past the hole in the casting around the dipstick tube?

Is the pcv working? What truck,what year,what engine? @SquareRoot look I caught another one. I wanted to help more but can't tell him where to check for pcv connection or valve cover breather with given information.

Bronze Knight said:

I'm feeling really stupid.

I cannot figure out this oil leak. I just did an oil change yesterday and put the UV dye in took it for a short test drive today < 1Mile and I had oil smoke particularly under acceleration from oil on the headers.

The UV dye seems to indicate that I've got oil coming out of the oil dipstick. but the dipstick is still seated in the tube after driving the truck. The oil is getting onto the frame rail somehow and running down it.

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Then there seems to be another leak that dripping onto the front crossmember. that may be the timing cover but I've done that seal recently.

You must be registered for see images attach

Does anyone have any ideas?

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Look we got another one!!!

That looks like a lot of oil for a pcv valve - even after new oil.
You should change pcv valves all the time though.

What kind of oil do u put in dere?

His profile says 1985 K30, so let’s assume that’s what he’s working on..
I’d definitely look at the PCV system, it’s not complicated, air in one valve cover, air out the other through the PCV valve. Or maybe valve cover gaskets, or the intake gaskets.

Sorry, all. Yes, its the truck in my signature. A 1985 Chevy K30 with a 454 and TH400.

The complete history on it is that it was a factory 6.2 Diesel, but before I got the truck someone swapped in a 454 (from a 73 truck, block casting #3999289 casting date A1273), and then heads on it appear to be from a 1966 Corvette (casting #3872702). It had headers on it when I got it. Though they were cheap and thin, I later replaced them with Summit brand headers. I don't think it's the PCV as that is plumbed right into the carb. I have done a lot of work on this truck so if anything looks wrong it's probably my fault. Here are some more pictures in the daylight. I know the driver-side framerail looks wet but that's power steering fluid fand it's not actively leaking did a hydroboost swap the other day. the UV dye just shows passenger-side oil leak.

If you guys want any more pictures or information let me know. I'm about ready to just drive it down to a local shop and pay to get it fixed.

I got nothin, other than she looks pretty clean!

Ya like them spinnin tires do ya?


Prolly oughta warsh it off and give us a fighting chance!

I don't see any pcv vent,Does 1 valve cover have a hose aboutt 3/4 of an inch in it running to the air cleaner housing. Or a breather in it? If the pcv valve can't draw air through that hose and through the engine to the other valve cover and through the pcv valve,or have a valve cover with a breather in it,then the engine can't vent,and it will push oil from anywhere it can. Fix 1 leak and the next weakest spot will be the leak. I suspect someone changed valve covers and didn't know how pcv worked. That was why I was ( what engine? ) because I didn't recognize the valve cover in your first pic. If they were factory on a newer engine my pcv comment would have been irrelevant,now that I know they aren't factory,they are my suspect. I don't read people's signatures,I read the post and address the problem,but even if I did it wouldn't guarantee that's what they are working on. Not chastising you just hope everyone reads it and realizes if they don't put year,model,drivetrain in the post it makes helping,harder . Have a great evening.

Ricko1966 said:

I don't see any pcv vent,Does 1 valve cover have a hose aboutt 3/4 of an inch in it running to the air cleaner housing. Or a breather in it? If the pcv valve can't draw air through that hose and through the engine to the other valve cover and through the pcv valve,or have a valve cover with a breather in it,then the engine can't vent,and it will push oil from anywhere it can. Fix 1 leak and the next weakest spot will be the leak. I suspect someone changed valve covers and didn't know how pcv worked. That was why I was ( what engine? ) because I didn't recognize the valve cover in your first pic. If they were factory on a newer engine my pcv comment would have been irrelevant,now that I know they aren't factory,they are my suspect. I don't read people's signatures,I read the post and address the problem,but even if I did it wouldn't guarantee that's what they are working on. Not chastising you just hope everyone reads it and realizes if they don't put year,model,drivetrain in the post it makes helping,harder . Have a great evening.

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Yep PCV vent was the issue. I swapped out the Valve covers when I put the engine back in and I did not realize that the old ones had a breather-style oil cap. So when I put the new ones on I plugged up the driver's side valve cover. I talked to my brother who used to be a mechanic about it over the weekend and he gave me a few things to test. One of those was to get the engine hot and then clamp off the line between the PCV valve and the carberator. I did that and at idle it would start puking oil out of the dipstick tube about 15 seconds later.



(It’s green because I used a whole bottle of UV dye)

So then I read up on the PCV system in the "Fuel, Driveability and Emissions Service Manual" and realized my mistake. Picked up a breather filter at the auto parts store put it in and clamped off the line between PCV vent and the carberator, again at idle, and this time I did not get oil coming out of the dipstick. So I took it for a test drive around the neighborhood again and I did NOT have a cloud of oil smoke coming off of my headers.




Still have a leak around the timeing chain cover. I’ll redo that with as much RTV as I feel I can and see if that fixes it. I may have to pressure wash the engine first to try and make sure it’s coming from the timeing cover.

Hate to be a party pooper but while you have solved one problem you've created another. Over time oil fumes from the engine are going to come out of your new breather cap.Oil will collect in the new breather cap and drip on your rocker arm cover and down to the exhaust manifold. Giving that nice clean engine bay a layer of engine oil.
The diagram has that rocker cover being vented to the air breather to recirculate the oil fumes.
When I got my square it had an air breather in the rocker cover. A pretty reddish Moroso one. Over time it started dripping oil. My engine bay was getting oily and smelling like oil more and more. I added the air breather vent hose, fuel pressure regulator and fuel canister and now the engine bay smells and looks a lot less like gassy and oily.
Before


After