Hey guys,

So my mechanic has been patching up oil leaks all over my baby and we're at a good place now but the last one we're trying to trace is coming out of the intake manifold. He tried replacing the intake manifold (cost about $620 with labor)

It seems that it is spilling out when I make a turn then hit the gas because I can smell oil burning and a plume of smoke in the rearview as I drive away. I don't know much about mechanics but assume somethings getting loose?

Anyways, have you experienced this or have an idea of what can be causing? I'll be taking her back to the shop Monday.

 

Engine oil does not circulate through the intake manifold. The manifold itself cannot be leaking oil. I would think your mechanic would know that.

I'm guessing the new intake was not sealed well when it was installed and oil can be leaking under the manifold. Check the four corners where the heads and manifold meet the block.

 

I would advise taking it to a different shop... $640 to guess about where oil is coming from and changing an intake manifold seems pretty steep. There should be no reason to change the intake unless it is cracked, or the gasket surfaces are totally mangled..

In my limited experience oil on the intake is either wicking up through a manifold bolt or leaking down from the valve covers..

 

sounds like your mechanic needs money real bad..

 

Can you see fresh oil anywhere on the engine

 

Maybe not for here, but if you have an oil leak you simply can not find, I've had luck with dye you simply add to the oil, clean ALL surfaces, then run it and look for leaks with a black light bulb....

 

There has to be more to this..I can't see a shop charging money for something that doesn't fix the problem..there are laws for this very thing..and its stealing clean and simple..it sounds like that when you turn and smell oil and see smoke is a new problem..hopefully they just screwed something up..or...they are scamming you..one other thing I thought of is do you have a vacuum modulator on your trans..not sure which trans you have but it does leak and suck fluid into the intake and burns it..in a turn you would be downshifting and a possible increase in vacuum would make it more evident..if I remember right a 350 trans has one and the 400 does not..I think..have you checked the trans fluid..anyhow a leak that you can smell and see when you take turns should be there at idle..start taking pictures of the engine compartment..write down numbers of the engine parts that are there..make sure the work being done is being done..oil leaks are NOT that hard to find on these cars!

 

That was my guess.

Happens every day.

 

Yeah Mike you're right..I guess I think that if it doesn't fix it then the shop should be held accountable for their wrong diag..I know I know its crap..I have seen it at every shop I have worked in over the years..at least the one now is little stuff..if there is such a thing! When I get ready to retire or sooner I will write a book called crooks under the hood..I have been taking notes for years..

 

well a very common place for oil to leak is the back of the intake if it was not sealed correctly. IF you dont get the mating surfaces clean before installing the intake then it will weep oil out the back and onto the exhaust.... ask me how i know.

Its free to crawl around with a flashlight and if you have enough oil leaking to cause that much smoke i bet you will spot it quick. Also check for oil weeping from the rear of the pan gasket (esp if its a 3 piece one) and from the trans pan. I have seen people torque the heck out of trans pans before and that will cause the cork gasket to deform and weep trans oil.

Good luck

 

The rear of the intake manifold & the front are know to let oil weep out. The rubber gaskets that come with the gasket kits really suck. I used RTV after cleaning the mating surface real good. Apply it and make sure the manifold sits straight down so it dosen't deform the bead of RTV and than let it sit for 24 hrs before starting so it can cure well. Do you have an aluminum or steel manifold?,steel can warp over time as I have seen with some original manifolds. Also valve cover gaskets dry & leak out over time which may be more of the culprit. Oil is always pooled up in the rear portion area of the cyl head as you can see when the valve covers are removed. Oil leaks are a never ending story with my C3. I just replaced my pwr steering pump and rebuilt the cylinder rod that were both leaking, also the control valve sprung one(aftermarket parts ) I just replaced the oil press sending unit due to a leak ( it was 34 yrs old though) I just replaced my chronic leaky cheapy chrome valve covers with the original goodwrench covers and fresh cork gaskets, the old gaskets were soaked & leaking & so far everything looks good. Oh yea the tranny pan gasket was leaking also due to the cheapy chrome cover deforming, I had to hammer that one out and seal it , seems to be holding up well for the past year.
Oh yea that mechanic guy sounds expensive.

 

Ok, so he said about $240 was just for the labor (he also went ahead and replaced my wiper blades in the total price too). I didn't make that clear on my first post so let me know if that is still unreasonable...

Second, check out the pics of the old intake manifold-I also forgot to mention the reason why he thought that was it was because it looked warped. And indeed it was visible it was from all the dark oil spots, but I didn't put a ruler on it to double check.




Now again, regarding whether he's screwing me or not. Replacing the intake manifold has DEFINITELY improved the oil leakage. It is truly a small fraction of how it was before up by that area.

I'll try to take a picture of how small the leak is tomorrow. But I'll also be taking it back to the shop tomorrow so I'll let you guys know what happens.

 

Well that's good..glad to hear its gotten better..not sure what book time is for an intake but can look it up tomorrow ..I could see 3 hours @80$ p/hr..I am not sure how dark spots indicate being warped..but I am not there to see it for myself..didn't realize the oil leak was that bad..so he started on top of the engine and will work his way down..have you changed the pcv valve yet..having tons of oil leaks can be an indication that its clogged or not working..have fun tomorrow ..

 

Oh my god. I'm an idiot.

So I went to the shop today, took a look around with the mechanic and the intake looked totally dry. I just glanced at it a few days ago and the small gleam of metal inside there must've made me think the leak was back.

Anyways, no more questioning, I think it won't be coming back.

Btw, the plume of smoke from a turn is likely from some left over oil droplets on the hoses--I'll get the engine cleaned out and that should handle it.

Sorry for the bad call guys...I'll let you know if it comes back.

 

Well that's great news..does that mean no more leaks!!!..at all anywhere.....oh I forgot..these are Corvettes that have a constant to do list...at least you can knock that one off your list!..awesome..

 

yeah thanks this is the last leak point we found, the first one was by the fuel pump, onto the next thing...control arms