Huge cloud of bluish white smoke, what happened?

[norcal pinz]

i was driving my Pinz down the highway today and i was going down hill and i looked at the spedo and i noticed i was going too fast. I was about 3/4 inch past 100kmh on the spedo i let off the gas and slowed down when i hit the gas again a HUGE cloud of smoke, bluish white came out the tailpipe for about 4 seconds completely covered the whole freeway behind me it stopped smoking right away and ran fine after that can someone explain what happened ??

[edzz]

When compression breaking your engine is trying to pulling air into the cylinder from where ever it can, if your valve guides are worn or your piston rings are worn it will suck air from those locations. When it does it will also be sucking some motor oil into the cylinder and burning it hence the mosquito fogging action. Also remember these engines don’t have valve guide seals.

Maybe time for a compression or leak down test to determine the condition of the engine.

Or it could just be that Mexican food diet you’ve had it on.

[pinzmeister-uk]

The breather pipe from #4 cylinder to the bottom of the oil filler pipe is blocked, take it off and clean it out or it will happen again.

[Jim LaGuardia]

One other item to check, if the rear seal on the brake master is bad, brake fluid will build up in the booster. The vac port is on the front side of the booster, going down hill and braking could slosh the fluid into the vac port and directly into the intake. I had this happen to my truck recently

simple to check, just loosen the master cyl mounting bolts and look into the booster .

[Jimm391730]

Also remember these engines don’t have valve guide seals.

Ahh, but they could have, at least on the intake guides. Seems that the Swiss didn't put much value on them and didn't replace them with all the rest of the repairs that they did.

Remember that the exhaust system almost never has a negative pressure (vacuum) in it so there is not much reason to suck oil from the exhaust valve guides, but the intake manifold always has vacuum (but at wide open throttle the vacuum is minimal) so oil can be sucked into the cylinders from them. AFAIK only the intake guides can have seals for this reason.

Yet in one of my engines the excessive oil consumption was due to worn piston rings, NOT the lack of intake seals (adding seals made no difference to my oil consumption until the engine was rebuilt by Jim L.). The other engine burns no oil at all, and I still can't believe it.

[edzz]

Also remember these engines don’t have valve guide seals.

Ahh, but they could have, at least on the intake guides.

Right you are Jim.

Someday I’ll have to check if my intakes “worn out seals” or none at all.

[StuartL]

The breather pipe from #4 cylinder to the bottom of the oil filler pipe is blocked, take it off and clean it out or it will happen again.

Could you elaborate on what's happening here? I'm curious

Thanks

[norcal pinz]

thanks for all the replies guys i will keep you guys posted

[krick3tt]

Of late my pinz is using a lot of oil, little more than a half quart in 150 miles. Used lots more on the trip to Portland.
That was 3300 miles. Really did not keep an accurate count then, just put in when it was low on the stick.
Lots of smoke on start up, sometimes but not always. What leaks out on the ground is about
a tablespoon as it appears on the garage floor drip pan. I'm thinking rings, sound about right? What is the best way
to check this out?

[edzz]

What is the best way
to check this out?

http://autos.yahoo.com/maintain/repairq ... 057_1.html

[cronapress]

I've got to go along with what Pinzmeister says. I've had this happen a couple of times. Quite spectacular when you glance in the mirror!. Yes, take that pipe off and give it a worrying with an airline - making sure the propelled gunge goes somewhere harmless. An alternative is what I now always carry in the box of bits - a pull through. A length of heavy gauge copper wire tweaked over at one end so as to grip a small piece of old rag. Pull it through the pipe - very satisfying!

It pays to check your oil level after a "make smoke" event. You can suck up and burn a lot of oil in a short time!

Lots of short runs that don't allow the engine to get hot enough seems to be the villain. The pipe accumulates oily gunge/mayonaise and leads to a blocked artery!

Mike 712M
Ayrshire.

[4x4Pinz]

what we have seen when a pinz just out of the blue puffs a huge bit of smoke is the loss of an oil ring. Quite spectacular to see when following and then oddly enough all is clear and it runs great until the next time. I have seen this happen while following a pinz that did this. I thought he blew the engine but he kept going. When we got to a stopping point I asked him about his truck and he said it had been doing it for some time and was going to do a top end. Now that the top end has been done his truck no longer makes these huge plumes of smoke, would have been cool to have filmed it happening.

[Jim LaGuardia]

Do a leak down test. A leak down test can be done two ways, both requiring the removal of the rocker arm assemblies. Once the rockers are off, pressurise the cylinders one at a time and listen for air leaks at carbs(with throttle plates open) to verify intake valves seating, then exhaust pipe for leaking exhaust valves, and last, remove the oil fill cap and listen for air leaking past the rings.
Normal leakage to crank case should not exceed 10% of input pressure and cylinders should be within 10% of each other.

[Winter Beater]

Jim,

Why remove rocker assbly? Could the test be performed when both valves are closed instead? How is the 10% measured?

[pinzinator]

I have done the compression test and the leak-down test on my 710, results were excellant and well within range. The engine uses oil just like every other one out there, so I assume that there are no intake seals. Not a big deal, but some day I want to install them.