Light wispy smoke out of right bank at highway speed

[ViviensTractor5110]

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

[AcampoDave]

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

[ViviensTractor5110]

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

[ViviensTractor5110]

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?

[geezer#99]

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

[ViviensTractor5110]

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

[geezer#99]

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

[AcampoDave]

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.

[68gmsee]

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.

[ViviensTractor5110]

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

[ViviensTractor5110]

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.

[AcampoDave]

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."

[ViviensTractor5110]

Same goes for Harley's...well said

[ViviensTractor5110]

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.

[geezer#99]

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?

[ViviensTractor5110]

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

[ViviensTractor5110]

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

[geezer#99]

Originally Posted by ViviensTractor5110

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

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.

[ViviensTractor5110]

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

[GASoline71]

Originally Posted by AcampoDave

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."

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

Gary

[ViviensTractor5110]

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.

[AcampoDave]

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.

[AcampoDave]

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?

[ViviensTractor5110]

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!

[ViviensTractor5110]

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