Obd1 slc smoking blue after warm up

[tkoral 6]

I've had a few vrs but none that smoked like this one.

The car is a 93 obd1 slc with 142k. I bought the car in the winter and took my time doing preventative maintenance stuff to it such as new heatercore, coolant pipe and housings, fuel pump, fuelfilter, plugs, cap and rotor. The car ran good when I got it and never smoked. A few months ago I installed coils on it and when I rolled it out of the garage it sounded like a lifter got stuck for about half a minute but went away. Changed the oil right after it did that but never took her for a drive. Keep in mind I only recently put the car on the road and have been driving it regularly for a few weeks.

The first week of having it on the road I noticed a tad bit of blue smoke at idle after warming up to around 190f. This evening I deleted the pcv pipe from the head to the intake. Plugged the intake and put a breather hose on the valve cover to a filter. Thought that was causing the smoke. As soon as I started her the smoke seemed to have gotten a lot more obnoxious It smokes at idle when warm and will puff a nice cloud when I rev her up. Oil temps while driving never exceed 220f and will be around 200f at idle. The car rips hard and the Mfa says it gets around 30mpg on the highway. Motor does t make any abnormal sounds. It's the quietest vr I've ever had. I plan on doing a compression test tomorrow.

Do you all think it's valve seals or guides or piston related ? All info will be greatly appreciated thanks

[VR6Pete 1,455]

Hi buddy.

 

Doesn't sound good! Blue smoke as you know indicates oil being burnt. but on idle sounds pretty bad. Are you using a lot of oil?

 

With you mentioned about the PCV delete, it could be throwing oil back into the intake manifold causing it to burn more oil, so I would personally restore the PCV valve to rule that out initially and check if you have oil re-circulating into your inlet manifold, of course you mentioned you used to get light blue smoke when warmed up, rings should seal a bit better when up to temp so unless you are hearing any slap when warming up it is "reasonably" safe to assume they are OK and to look at valve guides and seals. 

 

At 142k I would certainly say you will need to look at the condition of the head / valve guides and seals. Exhaust valve guides tend to start wearing after 80k and would tend to cause blue smoke when coming off the throttle.

 

What grade oil are you using? bare in mind anything too thin could cause it to smoke more with being a higher mileage - would recommend Syntha Silver 10/40 semi synthetic.

 

A Compression test will help of course, I have also read that if the readings are low in a cylinder to pour 1 teaspoon of engine oil into the plug hole and retest. If the reading jumps, the piston rings are worn. If not, then it will lead to a valve related issue.

 

Hope this helps! Please post up your compression readings later so we can help further  

 

Pete

[tkoral 6]

Thanks for the reply Pete I may put the pcv breather hose back in but the way I deleted it would make it impossible for any kind of oil to make it in to the intake manifold.

Only smokes when the motor warms up. I don't hear any piston slap whatsoever. It's just odd that it smokes at idle if it is the valve stem seals.

The oil that is in it is 15w40 non synthetic

Thanks for the advice on everything Pete I will be seeing what number she gives me in each cylinder after work

[tkoral 6]

Was able to do a cold compression test this evening.
#1 121 psi
#2 145
#3 140
#4 145
#5 132
#6 144

They are all within tolerances as I read in the Bentley. When I pulled the plugs out I noticed that number 3 was the only one with the porcelain showing a running rich condition all other plugs looked normal and clean.

Any advice or info will be appreciated

[VR6Pete 1,455]

Seems ok to me. Number 1 a little low but not unusual.

I would say that it's looking more like the valve guides and possible time to look at valve guides, although I can't think of anything that could cause it to only smoke once warmed up

[tkoral 6]

I think it may be consuming a little oil also. Ordered a used head to build up to be installed over the winter. If it's just guides or valve stems I'll be happy. Thanks Pete