smoke on start-up

boomy · Post by **boomy** » Tue Dec 07, 2004 1:55 pm

My 1.7 type 4 motor seems to run ok'ish, and doesnt seem to be running excessively rich, but recently I have noticed that when I start her up, I get great billows of smoke out the back.....its grey-blueish...could it be condensation burning off from inside the exhaust ? or oil ? It doesnt seem to smoke once up and running, and the only oil it looses seems to be through a leakey push-rod tube...

Piston rings ?

Nige · Post by **Nige** » Tue Dec 07, 2004 2:22 pm

Could be piston rings, though oil can settle in the bores with it being a flat configuration, mine did regularly tho it had done 180k and was pretty loose!

Not much help really

boomy · Post by **boomy** » Tue Dec 07, 2004 3:20 pm

Nige wrote:
Not much help really

...any help appreciated...thanks...

Robster · Post by **Robster** » Fri Dec 10, 2004 5:55 pm

Hi Boomy,

Rule of thumb is Bluish smoke is oil smoke. White smoke is condensation.

If it only does it on start up, and then after it has warmed up, the exhaust is 'clean', then it is probably worn piston rings. When the car is sitting idle, some oil leaks past them and sits in the combustion chamber which gets blown out on start up.

If it was valve guides, it would be putting out bluish smoke regardless of whether the car was hot or cold.
With worn piston rings, some of the combustion pressure will leak past, and pressurise the crankcase. If you have a seperate breather box, have a look for oil mist in there, or check your airfilter(s), you may see evidence of oil on the filter.

If you aren't burning excessive oil, you will get a small loss in performance, but I wouldn't worry too much. If your car is getting through loads of oil, but the car doesn't leave a pool of oil under the car overnight - then you have some serious piston ring 'blow by' and it's time for a rebuild I'm afraid....

Best of luck!

Best regards
Robster

Barry · Post by **Barry** » Fri Dec 10, 2004 7:39 pm

If you feeling brave (I aways dread this: its ostrich time) you could do a compression check if you can find a compression tester. Nice easy test, and will either help put your mind at rest, or give you something to plan for (future overhaul). The nice thing is, with this data, (assuming access to a tester) you can then repeat the test in a few months time to see if it repeats at about the same value, or whether things are going downhill.

Rules and tips for testing are widely available, but its pretty simple.

The Rolls Royce way of checking your engine's health would be to do a cylinder leakage test (I think that's what its called), where compressed air is introduced through the plug hole, and the amount of leakage accurately measured, this also tests valve seats as well. I wish I had the rig, but I have to use my ancient compression tester ...

boomy · Post by **boomy** » Mon Dec 13, 2004 11:51 am

thx for the advice guys...

Its really weird, I havnt noticed it for a few days....oil level isnt going down TOO fast either...

I think I will start a 'engine-rebuild' fund to run alongside the 'brake-rebuild' fund just in case..