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Smoke at the valve covers

Fatrat

Fatrat

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El Paso, Texas
Alright here it goes, I've read a few posts similar to this but not what i'm looking for. I have a 400 (carbed) in my 1990 blazer. It was running great then one day as i'm driving i a loud hizzing sound in the engine bay and tons of smoke coming out. I'm thinking a water hose broke, but my temp was at 175. I pulled into a parking lot and noticed that the valve cover breather on the passenger side was pushed out and some oil came out, not alot but enought to notice. At that time i only had breather on the valve covers, and smoke was coming out from them like steam engines, constant thick white smoke.

Anyways, i have since installed a PCV system and it helped, but the smoke is still there, just circulating around or coming out the air cleaner but not as much. If i take out the breather on the passenger valve cover tons of smoke comes out. I apologize for the lengthy post but the just trying to figure this out. The engine was freshly built 8 months ago. It has keith black pistons with foating pins, moly rings, and 6" eagle rods, the heads are vortec and were rebuilt with the engine. I spoke to the machine shop and they said to run it hard to allow the rings to seal and if it doesnt stop they will cover the rebuilt again. Tomorrow i will do a compression test to start, any other thoughts or comments are welcome, before i decide to pull it out. The engine only has about 250 miles on it since the build and its strong as hell, just the smoke issue.
 
It will smoke for the first 500 miles til the rings seat. It will have blow by tol then and burn a little oil. You should have a PVC onnone side of the valve cover and s breather going to the air cleaner in the other side to keep the gases flowing correctly. I would give it a couple hundred more miles to see if you got a problem.was the cam advanced. It could be the exhaust valve isn't closing all the way and its not burning all the fuel correctly. Just a couple thoughts.
 
The cam was not advanced, it was installed straight up. What gets me is that it was running fine. After i installed the PCV system (PCV on the driver side valve connected to a vaccum port on the carb base. Breather on passenger side valve cover connected to the air cleaner) i noticed that engine would not stay on, i was trying to re-time it just now and i had a hard time moving the marks. Thanks for the info, i'll run it more often, this is my off roader only (but street leagal), so i hardly drive it, guess its time to hit the long trails on open it up at the dirt
 
You have everything hooked up correct from what you say. I'm guessing everything hasn't worn in yet. I'd get it out and run it good for at least à couple good hours and then change the oil and look for anything weird in thè oil. Blown head gasket or cracked head will let water in the crankcase and the waterceill steam off and cause that too. Even so see if the oil is milky brown whitish on the dipstick. If not more than likely still need to brakè the engine in some more.
 
If the valve covers are not the original ones,they might be lacking a baffle where the PCV valve enters the cover--that'll let oil splash up into the PCV valve and let it get sucked into the intake and be burned...oil smoke would tend to be blue though,not so much "white"...white is usually water / steam or condensation burning off--or anti-freeze!...:doah:..I've seen flooded engine burn the gas off with a lot of white smoke too lately,I think the alcohol in the new gas absorbs a lot of water...
 
Did it have this much blowby right out of the gate, or has it increased? I would take it to that machine shop and see what they think of the blowby. In 250 miles, it should be sealed up pretty good.
 
The engine was running great, i took it on several trails with no problems. It drives very strong. I did a compression test today and they were all out of wack, #7 had zero compression. i backed out the valves a bit and got 165 on #7. once i redid the valves all cylinders were between 120 and 140. Seem high to me. Anyways i was able to time it and took it out for a drive, once again it runs strong, great response in all gears except the the smoke coming out of the air filter. BTW, once i adjusted the valves the smoke stopped completely, but after timing the engine, the smoke came back...bummer. I also noticed the engine was running hot, it usually runs around 170 to 185 at which time only one fan turns on, cools it then it turns off. Today it was running at around 200 and it had to reach 210 cuz both fans turned on. I'm thinking the heads.....?????????
 
The smoke coming out of the valve covers is going to be cylinder blowby. Basically the compression is bypassing the piston and pressuring the crankcase. I had this happen on the original 350 in my truck, several pistons worth of rings were laying in the pan when I tore it down. Probably explains the geyser of oil coming out of the dipstick :eek1:

In your original post you say the valve cover breather was pushed out of the valve cover, was that an actual breather or an oil fill plug?

Anyway, 0 compression on a cylinder and then adjusting the valves and getting compression and then losing compression when you set the timing has me :confused:. Are these hydraulic or solid lifters you are using and how are you setting the valves? When you said that #7 had no compression and then you adjusted, was #7 way loose or way tight initially?
 
Thanks for jumping in K20. #7 had 0 compression so i loosen both valves and checked it again at which time i got 165. then i went ahead and adjusted all valves by placing each cylinder at TDC and adjusting both valves 1/4 turn after the pushrod had no play. The lifters are hydraulic and #7 seemed to be tight at the exhaust which i thought it may be holding the valve open. Once the valves were set, #7 did not lose compression. Now that you mention it, when i removed the oil dipstick, the oil was coming out from the tube as well.
The machinist is being real cool about everything, he has machined many engines for me and this one is the only one acting up. he is willing to redo the entire engine, parts and labor free of charge. I have I have a 350 that i took out from a 94 burb just waiting to take the 400s place. I'll check the oil for shavings. also the breather on the valve cover that was pushed out is an actual breather that hooks up under the air cleaner via a hose.

You think i should just have the engine redone it would only cost me time to remove and install the 350. The 400 i can save for my wifes 2wd 72 C10 im building.
 
That valve not being adjusted is a problem. We're the other cylinders valve the same across the whole engine. Or just thè number seven. You wouldn't expect to see that on a newly rebuilt engine. Also compression should be about the same since this is a new rebuild. Either something in the rings isn't seated yet or broken or heads are off for some reason. Have you run it hard since adjusting the valves? Was the compression test wet or dry. It changes the ratio. Anything over 120 should be good enough to run correct.
 
any idea on comp ratio an cam? 165 psi is getting up there, I wonder if there was some detonation.

I would have them go through it, because I have never seen one that wasnt sealed up within a pretty short time. I really dont think the blowby is going to get better.
 
I adjusted all valves but only #7 was tight, all others were good. after doing the compression test (dry) i took it out and drove hard for about an hour on and off road but i didnt check compression after the test run. i was told the compression ratio was 11:1 with the combination of parts.. The cam is a comp cam part #12-212-2 grind #280H http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=79&sb=0 I think this is the link.
 
Well, even with correct cam timing, if you have the valves wrenched down to tight it will leave them open, causing that, but that will also tear the cam lobes or the lifters up being to tight as well.

And thats a decent machine shop, around here its a "taillight" warranty unless they install it and break it in.
 
Anything over 150 psi can't run on pump gas. It's going to need race fuel or severely retarded timing to not get detonation. You can get down the compression by using a thicker head gasket. I don't see that as being the problèm across the whole engine. All cylinders should be around the same compression. Is number seven Now under 150 after you readjusted the valves. Good catch on that by the way. You did good there. With the timing can you retard it a little and see what happens? On pump gas I've had luck retarding the timing and it helped with detonation. With your engine maybe 92 octane ain't enough to keep it happy.11:1 is up there where it may need something more.
 
#7 is still at 165, but all the cylinders are way different in compression which has me wanting to pull that engine and throw in the stock 350. Whenever i fill up the blazer i use 92 octane and ad a bottle of octane booster otherwise i do get detenation. the stock 350, as i mentioned is from a 94 suburban that was running great. I'm thinking use the 350 and sell the 400 to my uncle who loves racing. I just don't want to pull the engine, rebuild it, install it and have the same problem down the road. I'm taking the blazer to my uncles house this weekend to check it out and see what he thinks about getting it going good.
 
Something is way off if it had that much variation in compression. If the other engine runs good I'd put it in and run it. Sucks to have something like that happen. I'd give it back to the guy and have him redo it. I'd also do something to get compression to a more usable 10:1. If you plan fuel injection in the future it will compensate better with less compression.
 
Thanks chulisohombre, i was thinking the same thing. i'm debating on the MSD or FAST EFI systems, i'll look in those threads to see what everyone is saying. I also have a 383 block but no internals..mmmm, another idea. thanks for all the replies. and i will post any updates.
 
Alrighty, you said you set each cylinder at TDC and set them to zero lash + 1/4 turn? Not saying that is incorrect (I am doped up on nyquil at the moment, damn cold season), but I have always done each valve individually. For instance I want to set the intake valve I rotate the engine until the exhaust valve just begins to open then I set the intake. Reason being that with a more aggressive cam like I have in my 496 or you have in that 400, at TDC, one of the lifters might be starting to ride up the ramp. If that is the case you could have several valves partially opened by the lifters having too much preload

Have you done a cooling system pressure test? Follow my line of reasoning here (I might talk myself out of it by the time I get to the end of this), but if you had a cracked head or bad headgasket, water would go into the oil. Once hot this water would then steam off (producing the 'white smoke' out of the crankcase). That would explain why after setting your valves (engine cold) the smoke was gone but after you timed it (obviously engine running, possibly for a bit of time letting it heat up) the smoke returned. Also it could be that the crack only opens up once the engine is warm.

Also if you had a cracked head or bad headgasket this could allow compression into the crankcase causing it to push the breather out of the valve cover.

In the end I would have him fix the 400 and run it, once you have a built motor no stock 350 will make you happy, you will have it out 6 months later to have it turned into a 383.
 
Chris sounds logical, I doubt it's water in the oil because I can start it cold and as soon as runs the smoke comes out. What you said about the valves staying open makes more sense at this point. But I will do a cooling system pressure test this weekend sense it won't hurt anything. All good points even the fact that I won't be happy with a stock 350. despite the smoke, this 400 has alot of power and torque. My friend and my brother described it as scary fast.
 
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