Smoke from Rear of Block Under Intake Manifold

[DSMrunner13]

Hello Everyone,

History...
I just bought a 98 GSX rebuilt motor and trans (auto) . At what mileage was the block rebuilt and how many miles does the rebuilt block have is unknown. On the dash Mileage reads at 140,000. When i first bought the car there was white smoke coming out the tail pipe. I checked the turbo and i found shaft play so replaced the t25 with a 16g yesterday. Smoke out of tail pip has gone away. (Apart from this turbo everything else is stock).

Concerns...
Now another problem that I have found is that there is white/grayish smoke that is coming from the rear of the block/under the intake manifold area. I know that white smoke is usually related to coolant or turbo...but the turbo has been replaced and I do not smell a sweet scent from the smoke for it to be associated with coolant.

I also notice that there is white/grayish smoke coming from the cat converter. I can tell that its the original cat (140,000 miles)...so i eventually will change it.

Questions...
-I doubt it, but I was wondering if the smoke that is found in the rear of block/under intake mani can be related to the smoke coming from the cat?

-If they are 2 separate problems, then my biggest concern is what could be causing the white smoke under the hood? Head gasket? Maybe even oil pan gasket? I have heard of Intake Manifold gaskets being damaged or installed incorrectly while rebuilding a motor, could a bad intake mani gasket cause white smoke?

Additional Information...
-Apart from the smoke the car runs great. After swapin the turbo I did pulls on the highway and car feels good, block sounds good as well.

-Changed oil and filter (Mobil 1 full synthetic) also put fresh coolant 50/50 mix.

-There is no overheating issues at all.

Im new to the dsmtuner community this is my first post...all information will be greatly appreciated...thank you very much for taking the time.

 

[angelx]

There are many things that could cause smoke like this...

-As for the back of the block, you said it isn't coolant, but there IS a freeze plug back there. Worth checking with the mileage on the car.

-Your head gasket could be blown. You said the turbo was blown, yet whiteish smoke is still coming from the exhaust (and back of block), this could possibly explain both.

-Check your intake manifold gasket where your exhaust gas recirc. sits. I've seen the gasket burn up there (when oem) and cause a small amount of smoke/exhaust leak under/next to the intake manifold.

-Considering the location of your cat, it may just be smoke rolling up into your engine bay from the cat.

My first course of action would be take off/replace the cat since it is a known problem (so you say)

A boost leak/leakdown test should help you diagnose the issue as well since you think the IM gasket might be a concern

 

[DSMrunner13]

After I swapped the turbo the smoke out of the exhaust is very minimal to none. So is it possible to have a blown head gasket and not get smoke come out the exhaust?

I dont know much about that freeze plug but I will def look into it. I was suspecting the IM gasket so I will def look into that as well.

For the cat, unfortunately Im broke so I won't be able to replace that, but is there anyway I can perform a test to see if in fact the smoke is rolling up into the engine bay from the cat? Thanks a million

 

[angelx]

Idk about a "test" per say, but it shouldn't be that hard to locate where the smoke is coming from.

How much is the cat smoking? And is it smoking from where it couples to the exhaust pipes on both sides?

 

[DSMrunner13]

Ok so much of yest and some of today i spent looking at the car. I def dont think its coolant. I found an oil leak in the rear of the block which would tell me why i had white smoke coming out the top by the intake manifold. And to make matters worse...I started blowing white/grayish smoke again out the tail pipe (this is with the 16g with no shaft play).

The only conclusion that i can come up with is a bad head gasket...but again im not sure. Is there anything else that would cause an oil leak in the rear of the block?

And the cat is not blowing much smoke but def is some from that area.

Again thank you

 

[Coreyred95]

the oil could be coming from the valve cover/valve cover gasket. it could be dripping onto the exhaust and burning on the hot exhaust. and since you now have smoke coming out of the exhaust again i would be concerned about a bad head gasket.

 

[angelx]

he's right... that'd be #1 on my list!

 

[cutty2fast]

i had the same problem... in my case it was a small leak from the turbo drain leaking onto my exhaust and then the guy i had got the car from didnt have the pvc system installed so every now and again some oily sludge would burp out of there...

 

[DSMrunner13]

alrite i took the car to a buddies shop, had it on the lift, used 2 cans of engine degreaser, washed everything down, had the car idle and rev'd at 2000 rpm for a min or 2 while on the lift, shut off the car, removed the downpipe to create more room for visibility to the rear of the block...and while underneath the car i traced the leak...it was a missing bolt. Although im not 100% sure i think it was the balance shaft bolt. Please feel free to correct me if this is inaccurate (if in fact its not possible for a leak at this location). As for the smoke coming out the tail pipe i have a possible explanation. When under the car I had noticed that the initial oil leak had soaked the flex pipe...if the oil was seeping into the exhaust pipe through the flex section of the downpipe, (like some of you have suggested), then this is possibly the reason for the smoke coming out from the tail pipe. After cleaning the flex pipe i have not seen smoke out the tail pipe. Not sure if im in the clear quite yet. I plan on doing another oil change in the next couple days and will check to see if smoke redevelops. I will keep yall posted. Thanks to everyone who has provided suggestions.