7M-GTE Smoke Issues

[doobs]

Ey all,

A while back, I pulled my soarer off the road due to the excessive smoke that was coming out of the exhaust, and I presumed it was the turbo seals... There was lots of play in the shaft and to my knowledge it was a second hand turbo... I sent it off to JPC to be rebuilt, came back good as new.

Problem is, I still have a smoking issue. It has become better since the turbo rebuild, but its still happens.

It leaves me to look in 3 potential areas. Piston rings, Valve guides and stem seals, and the PCV system.

The test I have done so far... The smoke seems to happen in the following situations:

Most start ups, a smallish cloud of blue smoke will appear, but not all the time...
When the car is cold it seems to be slightly worse...
When decelerating from second to first, letting the engine coast down, not using brakes, a large puff of blue smoke comes out, and does for around 5 seconds after I come to a stop...
Some times when I’m sitting at traffic lights for instance as I take off I get a puff of blue smoke...
Under hard acceleration (flat to floor basically) from a standing start, there is a moderate amount of smoke in 1st, very little in 2nd, 3rd is probly too fast to notice...
When rolling along, and then accelerating hard in 2nd or 3rd, basically no smoke...

Compression test results are as follows (car was basically at running temp, did them twice)
No.1 = 170 PSI
No.2 = 175 PSI
No.3 = 170 PSI
No.4 = 175 PSI
No.5 = 175 PSI
No.6 = 180 PSI
They seem a bit high, but I attribute that to the fact the head has been shaved when I put the new head gasket on. When looking into the cyclinder, the tops of the pistons seem to have a bit of carbon build up on them, but they all look the same, and there is no oil in them.

After 150km on new oil, the oil seems fairly black, that may have been from the crook turbo, but could also be due to current issues. Oil pressure is all in spec.

I had the car teekay tested, there is no BHG, the car does not consume coolant, nor is there any bubbling. Car runs at about 80C.

Car audibly sounds fine, Idles very strong, and seems to go very very well, despite the smoking.

Here are some happy snaps of the plugs, In order from 1 to 6.







I'm hoping that its just the vavle stem seals, as I can repair them with out taking the head off, and I happen to have a set here, but I'm interested in what you wise toymodders think.

This has to be said... Before you reply, I'm well aware you 1JZ boys beleive your engine its the ducks nuts, and that all us 7Mers should turf our trusty old blocks, but seriously Id like to keep this on topic and not dribble on like most outher 7M based theads do.

After all that, any help will be greatly appreciated.
Thanx fellas.

[Kyosho]

If it's stem seals and valves, won't they show in a compression test also?

Hence I'd be looking at the PCV system.

[doobs]

If the vavles didnt seat right, then they would have an effect on the compression results, but AFAIK faulty stem seals wont effect a compression test at all, things like leaky headgaskets and bad rings/pistons would though.

As for the PCV system, I have no idea where to start troubleshooting that...

[EldarO]

me thinks you'd wanna look on the back of the intake valves/intake plenum, engine seems in good condition, so its not leaking through, but it is making it inside, my bet would be to start there, only place it cold come from.

valve stem seals may be causing your puff of smoke on startup and after idling for ages, but nothing that bad, unless they're completely clapped out.

Elmo.

[lexsmaz]

Pretty much the symptons that you give are valve stem / seal issues ....
To retest, start the car up & drive till warmed up then pull up & let it idle for a couple of minutes then give it a quick rev up to say 3,000 ...but dont hold it at 3,000 rpm just stab the throttle, if it blows a lot of smoke 90 % probability valve stems seals ...
Next test is again stationery, bring the rev's up & hold them at say 4-5,000 rpm hold for at least a minute, if you get a solid column of smoke coming out the exhaust whilst holding the revs, 90 % probability worn rings, can never be a 100 % until you pull it down ..
Personally pcv issues are very rare, unless you have played with the breathers, etc,..or the motors all clogged up & the oils not draining back to the sump ...

[doobs]

Well I have replaced all 24 steam seals, and still im getting the same symptoms... I've also cleaned the stock PCV system and then installed a catch can, with no change.
I'm in the process of teaching myself whats involved with a leak down test, then I'll do that.

I can stop it from smoking by not engine braking, so I will do that until I can get a better idea whats wrong, Im thinking, despite the good compression results, the rings are sick.

[Kedderz]

correct me if im wrong but isnt smoke on engine compression braking is rings isnt it?

[doobs]

It makes sense that it could be the rings....

I will do a leak down test as soon as I can get a tester, all should be revealed then.

Edit: found instructions, Ill just build a tester at work

[Kedderz]

hope for your sake its not mate

[doobs]

Thanx dude, but I think I'm on the money... and most likly up for some...