Ad Radar
12 Last
Item Posts    Sort Order

Burning alot of oil, great compression... Valves, Valve Guides???

 
Brenner2009
I love my Chevy Chevette!
Posts: 1
Joined: 08/09
Posted: 08/20/09 07:41 PM

I just purchased a Jeep Grand Wagoneer with a Chevy 350 stroked to a 383 (5000 miles on completely new engine). About a week after i bought it, it began to burn alot of oil. Clouds of blue smoke exit the tail pipe when you put on the gas. Upon start up it will let out a small cloud of blue smoke, the engine will run fine until it warms up, once it does the oil burn becomes more pronounced (a combination of light blue smoke and actual unburned oil exiting the tail pipe) and then engine begins to run very roughly when you try to accelerate at more than a crawl. To the point where i have to put about a quart of oil in it everytime i drive it (about 20-30 miles).

The engine always runs cool, at about 180 degrees, never hotter.
I just performed a compression test with the results of 190 PSI +/- 5PSI on each cylinder which leads me to believe that the piston rings are not bad and seated properly. The engine does not leak oil anywhere.

This is about where my mechanical knowledge runs out. Would this indicated bad valve seals, a stuck valve, bad valve guides? Please help?

Also please offer any thoughts on roughly how much this might cost to fix. Should I pull the engine and bring it to a shop on an engine stand or leave it in and allow them to perform more tests.  

Post Reply
waynep7122
I mow my lawn and find Chevys
Posts: 1130
Joined: 08/09
Posted: 08/21/09 06:33 AM

valve seals...

valve guides...

drain back holes in the head...

leaking intake manifold gaskets..   leaking from the bottom side..

incorrect pcv valve...  or the baffles in the valve covers are not doing their job... no breather on the other valve cover..

are the #5 and #7 spark plug wires separated??? if not .. you might have detonated the piston...   it should show up with reduced compression.... but it does happen..


you can tell with the engine idling.. block off the breather hole in the valve cover.. and then block the pcv hole with your thumb or finger.. you should have some pressure build up... if you have suction there ... the intake or intake gaskets are leaking ..  

Post Reply
Pontiacman2
Moderator
Posts: 8956
Joined: 09/08
Posted: 08/21/09 07:18 AM

What work was done to the heads.  
Pontiacman2
Pontiacman2

Professional Hi-performance engine builder

Post Reply
zman123
Everything in my driveway’s a Chevy
Posts: 537
Joined: 06/08
Posted: 08/21/09 07:58 AM

Very strangely familiar, I am having a similar problem. Just on the passenger side. sometimes smoke, never when it's cold, sometimes a big cloud when I stasrt. Less than 3000 miles on the engine. KB pistons, Total seal rings, Edelbrock RPM heads and intake. Had that head off 4 times now, had the guides checked, replaced the seals,even changed intakes thinking that might be the problem same thing. had the head and intake checked for straightness at the machine shop, made sure the rocker stud threads on the intake sides are all sealed with thread sealer . Had it dynoed last week 310 HP at the rear wheels, 375 foot pounds torque, runs fine but the smoke thing is making me want to put the old motor back in. Have not tried the PCV test yet, engine draws 17 inches at idle.  

Post Reply
p2-72chevelle383
I mow my lawn and find Chevys
Posts: 1760
Joined: 08/09
Posted: 08/21/09 08:42 AM

I had the same problem with my 383. I was sucking oil through the pcv and would really blow smoke when i got on it and would foul the plugs. take the hose off the pcv and blow in it if oil comes out then thats your culprit.I used one of those breather caps with the little snorkel thing on the side and hooked my pcv to it with a piece of hose then to my carb with a regular breather on the other side and it cleared it right up  
p2-72chevelle383

Post Reply
zman123
Everything in my driveway’s a Chevy
Posts: 537
Joined: 06/08
Posted: 08/24/09 06:40 AM

Tried switching to a different PCV, did the test as suggested, a little pressure build up from the crank case so no internal vaccuum leaks, switched to a new PCV for a 69 corvette, seems to smoke a little more but that may just be residual oil. I will run it this way for a while and see if it clears up, any more suggestions out there?  

Post Reply
Zacko
I love my Chevy Chevette!
Posts: 13
Joined: 08/09
Posted: 08/28/09 11:00 AM

Also make sure your valve cover has the baffle on the pcv valve side. Oils splashed around by the rockers can get sucked up pretty easy if that baffle isn't there.  

Post Reply
zman123
Everything in my driveway’s a Chevy
Posts: 537
Joined: 06/08
Posted: 08/28/09 03:09 PM

I decided to eliminate that possibility, took the PCV out of the equation         re adjusted the carb and now have breathers on both sides for now. I'll drive it and see what happens.  

Post Reply
mpayne
I mow my lawn and find Chevys
Posts: 1117
Joined: 10/07
Posted: 08/31/09 02:27 PM

Hopefully nothing bad happens to the engine.  

Post Reply
zman123
Everything in my driveway’s a Chevy
Posts: 537
Joined: 06/08
Posted: 09/02/09 06:48 AM

What possibly could happen? Drove it 200 miles yesterday on the freeway (@ 21 MPG), it has not smoked at all, I think oil may have been sucked into the engine through the PCV. The inside of the hose going from the PCV to the carb was wet with it. There is a small ammount of positive pressure coming from the crankcase (total seal rings), so no internal vaccuum leaks to lose oil from. I put breathers on both valve covers so there is nothing to keep the pressure in the crankcase. Am I missing something?  

Post Reply
p2-72chevelle383
I mow my lawn and find Chevys
Posts: 1760
Joined: 08/09
Posted: 09/02/09 06:58 AM

sounds like that same situation as mine it has never given me problems again good although i still run a pcv through a breather cap outside the valve cover its just better for a street motor.but i have seen plenty of street motors with two breathers just keep up on those oil changes and youll be fine  
p2-72chevelle383

Post Reply
zman123
Everything in my driveway’s a Chevy
Posts: 537
Joined: 06/08
Posted: 09/02/09 01:38 PM

Before the smog police there were no PCV's and engines ran just fine  

Post Reply
mpayne
I mow my lawn and find Chevys
Posts: 1117
Joined: 10/07
Posted: 09/02/09 02:46 PM

Damn those smog police, if they were not around I could have saved $500 when my cat went out in my van.  

Post Reply
SMOKESHOW
I mow my lawn and find Chevys
Posts: 1001
Joined: 09/08
Posted: 09/02/09 06:55 PM

or you can weld in a $90 converter from catco.  also the smog laws are a pain in the ass, but we need to use this planet for a while!  

Post Reply
Pontiacman2
Moderator
Posts: 8956
Joined: 09/08
Posted: 09/03/09 06:26 AM

I agree.  
Pontiacman2
Pontiacman2

Professional Hi-performance engine builder

Post Reply
12 Last
TO TOP