Valve guild/stem worn or not worn (1 Viewer)

[love2fly]

I have been tracking a small amount of oil usage (1/4-1/2 qt. every 200 miles) that is taking place on a 2F engine with around three thousand miles since a complete overhaul.
Today I was warming up the truck with the hood open doing some engine compartment checks and went to rev the engine by hand and saw a large amount of what looks to be blue smoke not white blowing out the exhaust on the rev. I let the engine idle for a minute and load up and rev again and get the same puff of blue smoke the goes away. I can rev again right after the 1st rev and get nothing so it needs to idle for around 30 seconds to get the same blue smoke results.
I was wanting to ask if any of you guys know a way to maybe positively ID that the valve stem seals can be the problem or have to rule them out.
I have checked the PVC, air filter, mixture, float bowl setting, all good.
Any help is welcome.
Thanks

 

[fjc-man]

A cylinder leakage test to eliminate whether or not it’s the rings or valve guides. Oil deposits on one or more spark plugs?

 

[Marn0]

Sure sounds like stem seals to me. Smoke on startup and after idling

 

[love2fly]

I have a compression gauge so maybe that would be the start area. I will pull the plugs to see what condition they are in today.
I appreciate the reply's.
Thanks

 

[Tancruiser]

Half a quart in 200 miles is a lot ,is the blue smoke present all the time or just at start up?

 

[love2fly]

Yes that's why my concern and it maybe a little less than a half qt. but any use is a concern. I know there will be a little brake in use after rebuild but this many mile latter is questionable.
There was some radiator water loss that I found but after a radiator pressure check it was the cap that was not sealing all else sounded and looked good - no hissing or dripping. It was even a newer cap from the first of the year.
It seems only after a cold start up and until it reaches op temp. Honestly I did not check it after a long drive. I am going to run it today for a few miles and rev check it and see if it continues and I will let it idle and rev again to see if it only on cold start ups or even when hot. After I will let it cool for a bit then check the plugs and give it a compression check.
Thanks

 

[fjc-man]

So I saw that you said you checked the PCV. The valve (can blow through both ways, more one than the other) isn’t installed backwards. If you disconnect the hose from the intake side of the valve (running) you should have created a vacuum leak. If not, the connection pipe on the intake manifold is clogged solid with carbon buildup.

 

[love2fly]

Yes did check pulls in only one way and not out the other. With it removed and engine running I can put my figure over the PVC end and feel the suction, removed and cleaned (Toyota part) PVE and spring seats and seals with vacuum applied.
Thanks

 

[SteveH]

In my experience, bad stem seals show up as blue puffs when you upshift. Do you ever see those? To me, smoke when you rev the engine is bad ring sealing.

 

[fjc-man]

If you don’t have an FSM, this shows how to test.

 

[love2fly]

Yes I did do that inspection as per manual and the valve is in good working condition. While doing the inspection I did notice that the PVC hose looked a bit flat at one side were it goes over the rocker cover at a 90 were the valve is connected. I took a better look and did not like it, felt as the hose was thin and prone to possible collapsing in high vacuum and it was thin carb hose. I took a leanth of aluminum tube and bent it to were it would run over the valve cover and down both sides and linked it to the PVC and intake nipple with a short section of the old hose. This will stop any collapsing and restriction from a rubber hose. Still have puffs of blue smoke after that install and a few mile ride.
Checked the S-plugs and they looked fine, so I did a compression check with these findings.

front to rear:
1 - 105 psi
2 - 103 psi
3 - 105 psi
4 - 106 psi
5 - 106 psi
6 - 107 psi

I don't have a gauge to do a leak down check but I am starting to feel as the stem seals are the problem unless someone has a other suggestion.
Thanks guys.

 

[pb4ugo]

Those compression #s are really low for an overhauled engine. You should do a compression check with a hot engine throttle wide open. Then do a wet compression check. Squirt a little oil in the cylder and then check the compression. If the #s increase significantly, then it's the rings. If the #s stay the same or slightly increase then it's the valves or head. If the engine blows smoke at the initial start up then clears up would indicate valve guides or seals. Oil has seeped past the seals and guides and leaked into the cylinders. If the engine smokes on down shifts, deacceleration, or engine braking would be an indication of worn old valve seals and guides. During deacceleration the carb throttle plates are closed and the engine is searching for air for compression and sucking oil thru the seals and guides. From what you describe smoke on throttle up I'd guess rings.

Proper PCV hose is a type of hose designed not to collapse.

 

[love2fly]

Yes they are low compared to 140 as a norm but an hour ago I was thinking about the numbers and flashed in my head that I had forgot to open the throttle all the way prior to the test so I will have to redo it tomorrow. I may hopefully end up with 30-40 more psi to those readings.
The PVC hose was in the truck when we got it and looked good at the time but as said now it does not make me feel as it is enforced enough to stop from collapsing at a high vacuum.
Will re-post my compression findings tomorrow. Oh the last one was done hot.
Thanks

 

[SteveH]

Now that you have compression numbers, have you started the engine and removed the oil filler cap (while it's running) to see if there is a breeze (or smoke) coming out? If there is a lot, then this typically indicates a problem with the rings.

 

[love2fly]

Yes I did that a few time prior to starting this troubleshooting. No smoke and no air being pushed out due to ring bypass. I am leaning now to it is the seals and will start looking for a good set (12) of stem seals. I believe Enginetech company use to sell a new line of seals (better rubber) so will check with them, flelt - pro not sure of as the overhaul kit install was a flet - pro kit. Had all new ex and intake vales (stock) installed should of been no problem.

 

[fjc-man]

Do you know if the valve guides were replaced?

 

[love2fly]

Yes the valves were with guides, springs, cap and locks when bought. New bearing, pistons, rods and so on. Cam was checked and as was the crank shaft.

New reading from a correct compression check:

#1-150
#2-145
#3-149
#4-145
#5-150
#6-148

 

[Tancruiser]

Those numbers look good at what altitude do you live? I’m at 8100 feet and that’s about what I got on mine after a rebuild . I’d put a vacuum gauge on it and see what it pulls.

 

[pjohnson]

Is it possible you just have a couple seals that are not fully seated? Maybe you can tell visually?

 

[love2fly]

Vacuum reading steady no late timing or valve leaks. 4,000'
I guess I will have to pull off the cover to do just that and take a look. I did not know that the seals were to stay in place or be fully seated as you said. The seals have that lip on the bottom so I presume they are held in place somehow. Will be taking a look at in between the springs in a day or two. Would be a good time to have the valve cover powder coated anyway.
Thanks