Light wispy smoke out of right bank at highway speed
 

Ladies, gentlemen...

I'm grateful to be back in an audience with some of the most knowledgeable people around...fresh off a banning from our beloved board.

Anyways...I recently dumped the 250 and threw in a small block 400. Motor runs great aside from this scary fact...when I reach highway speed a very faint trail of smoke is left behind my right exhaust. I know it could be a million things, the curious part is that it only occurs at 2500+ rpms cruising...not necessarily under hard acceleration. Start up...low rpms..idle..acceleration are all clean. Any insight is very much appreciated.

The plan is to start yanking plugs tomorrow and going through the motions but I'm a little freaked and need to borrow a compression gauge as yet...wondering if anyone has seen similar...hopefully something stupid like a valve guide or clogged breather but I'm not lucky enough for that.

As a side note it runs ice cold...160 with no shroud...before all the steam hole Siamese cylinder talk starts.

Thanks again

Re: Light wispy smoke out of right bank at highway speed
 

A bad intake gasket caused my my truck to smoke out one side.

Re: Light wispy smoke out of right bank at highway speed
 

I should also state that my coolant appears clean and the level is steady, pan gasket is shot so gauging consumption is inaccurate at present, though the condition of the oil is habitually inspected and it appears as it should- no milk

Re: Light wispy smoke out of right bank at highway speed
 

That's the kinda optimism I'm hoping for! Encouraging!
Thank you
My crazy self automatically thinks cracked head when things like this happen.
Did it occur at all rpms consistently or at speed/ under load?

Re: Light wispy smoke out of right bank at highway speed
 

Is it blue, white or black?
Do you have a working pcv?

Re: Light wispy smoke out of right bank at highway speed
 

greyish....light in color. PCV is new.

Re: Light wispy smoke out of right bank at highway speed
 

Put a 195 thermo in it and see if it changes it!
Could be incomplete combustion due to being too cold.

Re: Light wispy smoke out of right bank at highway speed
 

The intake gasket problem pretty much smoked all the time. The gasket was all oily when I changed it and the crappy seal simply let it get sucked in from below.

Re: Light wispy smoke out of right bank at highway speed
 

Can you see the exhaust at cruising speeds? I find it hard to determine a slight leak when driving down the road unless it's really bad or have someone drive behind me that is familiar with the darker/grayish color of fuel, bluish color of oil or white to light gray color of coolant. Sometimes these colors are very subtle and hard to determine but the best way to know for sure is to have a shop with engine exhaust analyzer check it for you. The better ones can analyze even minute amounts exhaust that one can't see at idle.

One other comment. A compression test may or may not determine a problem with valve guides and/or head gasket unless the gasket leak is severe. A leak down test is better in this case.

Re: Light wispy smoke out of right bank at highway speed
 

All excellent information...thank you...had the wife behind me...she advises it's darker than white...more gray...and only occurring at speed...and very faint at that...the temp thing could certainly factor...it only being on the right bank worries me

Re: Light wispy smoke out of right bank at highway speed
 

May have gotten my panties in a wad over nothing...pan gasket was losing oil on the passenger side header.....hopefully the source of my smoke...changed pan gasket and made a lovely discover....two bolt splayed mains! And a GM HV pump. I'll update on the saga when she's turning again. Thanks for everything.

Re: Light wispy smoke out of right bank at highway speed
 

I love chevys but my buddy and I have a saying, "There are only two kinds of small blocks, those that leak oil and those that don't run."

Re: Light wispy smoke out of right bank at highway speed
 

Same goes for Harley's...well said

Re: Light wispy smoke out of right bank at highway speed
 

Ok...so it's not the pan gasket. The holes near the fuel pump: top (usual suspect) is plugged as is necessary. The bottom is open but feels like a blind hole...oil is gushing from somewhere...primarily on the left hand side and at or below the pan gasket line. Gushing...thought about front main but dampener is dry and its splash oiled so I don't think it would gush like that.

Re: Light wispy smoke out of right bank at highway speed
 

Usually oil gushers are caused by crankcase pressure but you said your pcv is working right.
Or is it?
Got a pic of your motor?
Also what tranny you running?

Re: Light wispy smoke out of right bank at highway speed
 

Pcv is new...it's an early 70s 400 motor with an RV cam and splayed 2 bolt mains...and it's driving me up the wall. Trans is an sm465

Re: Light wispy smoke out of right bank at highway speed
 

The only thing that I can think to check next is the fuel pump plate gaskets

Re: Light wispy smoke out of right bank at highway speed
 

Good idea!!
I had a crankcase pressure problem once and that's where the gasket blew out.
I've also encountered bad pcv's and chrome breathers like yours that are closed inside.

Re: Light wispy smoke out of right bank at highway speed
 

I replaced both the breathers...I just hope it's that pump plate, I'm running out of ideas...thanks for the help

Re: Light wispy smoke out of right bank at highway speed
 

If a SBC ain't leaking oil... it's out! :lol:

Gary

Re: Light wispy smoke out of right bank at highway speed
 

Did the fuel pump plate gasket and I'm still losing oil!!!! Can't figure out where the hell its coming from and it's blowing out like crazy. Everything that I can think to plug is plugged journal hole wise. It's something dumb I just know it.

Re: Light wispy smoke out of right bank at highway speed
 

My only immediate thought is just to clean the motor top to bottom at the car wash, and get it up on ramps in order to visually locate the problem. That is how I discovered my leaky rear main on my 283. I layed under there with a powerful flashlight and watched it run without the clutch cover on it.

Re: Light wispy smoke out of right bank at highway speed
 

Could it be something like a valve cover or the oil pressure sending unit? A fan can make a leak look like it comes from everywhere. After all you already adressed the pan, fuel pump, the holes in the front of the block by the fuel pump, you checked at the balancer/timing cover, there isn't much left at this point but the valve covers, rear main, pressure sender/gallery plugs and what about where the timing cover meets the pan?

Re: Light wispy smoke out of right bank at highway speed
 

I think I got this bastard....like you said running out of things...started looking at the creases around the head...looked wet...decided I'd try the intake...ripped it all down...started pulling the manifold itself....half the bolts were finger right. This has to be it!

Re: Light wispy smoke out of right bank at highway speed
 

And then the rain blew in my carport too much to continue so tomorrow it is.

Re: Light wispy smoke out of right bank at highway speed
 

Wow, I remember rain. Keep us posted. My only reservation on the intake is your description of "gushing oil". There really isn't any kind of pressurized source for a leak with regard to its' seal to the block. My smoking problem was an intake problem, but the smoke was coming out the tailpipe.

Re: Light wispy smoke out of right bank at highway speed
 

Where is your pcv valve located? In the pic you posted there appears to be a breather in each valve cover.

Re: Light wispy smoke out of right bank at highway speed
 

I'll keep you guys abreast of this,....my ongoing nightmare. I have a breather in the passenger side and a breather style pcv in the other side...mr. Gasket I believe. Had the click style at one point and it behaved the same way as far as the gusher goes. Surely there must be galleys under full pressure in there since my oil pressure gauge is threaded into the intake. Fingers crossed and thanks for all the support.

Re: Light wispy smoke out of right bank at highway speed
 

You better look at that again!
Your oil pressure gauge shouldn't be in the intake. No oil passages thru there.
Any time you've got a leak that gushes, you have a leaky pressure connection or excessive crankcase pressure.

Re: Light wispy smoke out of right bank at highway speed
 

So that threaded connection in the block?....way in the back next to the distributor...haven't completely removed it yet so I can't tell.

Re: Light wispy smoke out of right bank at highway speed
 

That one is on the block not the intake and it one of the oil pressure connections. There should be another by the oil filter.

Re: Light wispy smoke out of right bank at highway speed
 

That being the case then I guess I'm chasing crank case pressure issues...since I've expended every possible galley under pressure

Re: Light wispy smoke out of right bank at highway speed
 

Thankfully you guys talked me out of anything catastrophic....I know it's something ridiculous. Just have to find it.

Re: Light wispy smoke out of right bank at highway speed
 

The biggest problem created by crankcase pressure is the multiple different leak locations. You fix one and the next one starts to leak.
Keep at it!
You'll find it!!

Re: Light wispy smoke out of right bank at highway speed
 

I usually remove the oil filler cap and feel to see if there's excessive pressure (blowby) from the crankcase. Should be very little if any on a good engine.

If you haven't found the oil leak already, as Ocampo Dave mentioned, wash the engine really good. Oil tends to travel and sometime difficult to find. When looking for hard to find leaks I buy a couple of cans of degreaser and pressure wash the engine really well. Then I use a mechanic's mirror and a flashlight for hard to see places.

I've had leaks on the rear of the valve cover and the rear intake gasket and oozing out of the oil sending fitting on the engine. The most common ones are of course oil pan and valve cover gaskets. Also, the rear main seal and front timing chain cover.

Re: Light wispy smoke out of right bank at highway speed
 

Well...whatever it was, it is no longer. Thank god.

I was ready to drive it into the river.

Re: Light wispy smoke out of right bank at highway speed
 

Thanks for all the perspective guys.

Re: Light wispy smoke out of right bank at highway speed
 

I'm sure glad!!
Was getting tired of your posts!! LOL!!!
Now lock the hood shut, put on your shades, never look under the truck and never ever let the wife follow you to look for smoke and get out there and drive the wheels off it!!