Has my Catalytic Converter gone bust?

Mint · Post by **Mint** » Tue Nov 22, 2005 9:21 pm

When i start my engine, a huge puff of thick smoke comes out of the exhaust. Sometimes the car won't even start first time. The smoke continues to come out of the exhaust for about ten minutes and then it clears, so that the only emissions are steam. I'm wandering whether this is a problem with the Catalytic Converter or is there anything else that may be making my engine unhealthy? I'm completely new to the car scene so basic terminology is a must! I have a 1997 Polo 1.0 L.

Many thanks

Mint · Post by **Mint** » Tue Nov 22, 2005 9:27 pm

Oh and by the way, its done 84,000 miles if this helps. It has a service history but i havent done anything with it since i bought it on the 23rd of October.

Blackone · Post by **Blackone** » Tue Nov 22, 2005 9:47 pm

Black, Blue or white smoke?

Bearing in mind with the cold weather that we've been having lately whilst your engine is warming up, you'll get clouds of whitish smoke coming out.

Has this problem just started, or has it been around for quite some time?

Mint · Post by **Mint** » Tue Nov 22, 2005 10:00 pm

It has been happening since i bought it ( a few weeks ago ). Its a thick blend of blue/black smoke which slowly dies down after a few minutes of driving.

Blackone · Post by **Blackone** » Tue Nov 22, 2005 10:18 pm

Blue black indicates its burning oil, does it smell like burnt oil!!

Could be your valve stem seals.

If it smokes all the time then maybe its piston rings.

Is the car running ok other than the smoke?

If your car is burning oil, then depending on how bad it is, that could bugger up the kat as well.

Mint · Post by **Mint** » Tue Nov 22, 2005 10:22 pm

Yes it smells horrid. From what you've said about seals; it doesn't sound nice so im guessing ill have to take it to a bloody garage. No wander it was so cheap. Other than the start-up smoke, it runs as sweet as a nut. Something i should also tell you is that when one of my friends unscrewed the cap for the air filter, there was oil in it. He said that needs cleaning out and doesnt understand why there is oil there as it shouldnt be. Does anyone know why this is here to?

Thanks alot.

bstardchild · Post by **bstardchild** » Tue Nov 22, 2005 11:22 pm

Mint wrote:Yes it smells horrid. From what you've said about seals; it doesn't sound nice so im guessing ill have to take it to a bloody garage. No wander it was so cheap. Other than the start-up smoke, it runs as sweet as a nut. Something i should also tell you is that when one of my friends unscrewed the cap for the air filter, there was oil in it. He said that needs cleaning out and doesnt understand why there is oil there as it shouldnt be. Does anyone know why this is here to?

Thanks alot.

The engine is breathing heavy so blowing oil into the airfilter box

Take the oil filler cap off when the engine is running and it will be puffing air - a lot......

Piston rings is my guess - and that will be expensive unless you can do it yourself

Mint · Post by **Mint** » Tue Nov 22, 2005 11:30 pm

Oh....thanks. Looks like ill have to begin saving. At least i have an idea as to what is causing it now. .. Piston rings whatever they are; why couldnt cars be as efficient as humans

loud · Post by **loud** » Tue Nov 22, 2005 11:50 pm

check your dip stick and make sure the oil isn't filled over the maximum

warrmr · Post by **warrmr** » Wed Nov 23, 2005 8:36 pm

Mint wrote:Oh....thanks. Looks like ill have to begin saving. At least i have an idea as to what is causing it now. .. Piston rings whatever they are; why couldnt cars be as efficient as humans

there rings of metal that clip round the pistons to make a seal betwen the boresand the piston. they stop the oil comeing into the combustion chamber and the air/fuel mix getting into the oil.

Mint · Post by **Mint** » Thu Nov 24, 2005 11:42 am

So do you agree that its the piston rings creating the smoke? I did and oil, air and both filter changes last night and the smoke has cleared. It still smells funny but there is much less smoke and its whiter now.

Regards

Mint · Post by **Mint** » Thu Nov 24, 2005 11:49 am

I also took out the air filter box and used an engine degreaser spray to clean it as there was small amounts of oil in it. Is there any way of checking whether the catalytic converter is knackered? Im guessing that because the exhaust fumes smell, it isnt properly filtering the emissions. The car is 8 years old so there is little point in replacing the cat converter if its so expensive to repair - ill send the car to the skip and buy a newer polo if i can. Any help is appreciated

Regards

bstardchild · Post by **bstardchild** » Thu Nov 24, 2005 12:30 pm

Mint wrote:I also took out the air filter box and used an engine degreaser spray to clean it as there was small amounts of oil in it.

Good move

Mint wrote:Is there any way of checking whether the catalytic converter is knackered?

Emission test will tell

Mint wrote:Im guessing that because the exhaust fumes smell, it isnt properly filtering the emissions.

You've got it the wrong way round a bit....

Cats always smell - nature of what they do.

What Cats can't cope with is large quantities of unburnt fuel and oil

It does not filter but convert or catalyze exhaust gasses - it is designed for an engine that is in good condition and well maintained - it is not designed to clean up the emissions of one that is badly maintained or reaching the end of it's service life

If you run a car with a missfire it will cause unburnt fuel to go down the exhaust - this creates uncontrolled heat as it burns on the cat - destroying it's ability to catalyze

Oil vapour or smoke has pretty much the same effect - if there is a lot of it some will get through the cat and out the tail pipe

Mint wrote:The car is 8 years old so there is little point in replacing the cat converter if its so expensive to repair - ill send the car to the skip and buy a newer polo if i can.

It sounds like the engine wear has reached it's limit and replacing the cat will just be a waste of money if the engine was still tired

Mint wrote:Any help is appreciated

You've got what I know

warrmr · Post by **warrmr** » Thu Nov 24, 2005 1:52 pm

if your a competent mechanic or if your good with your hands. go down the route of dismantling the engine and checking all routes that oil could get into the chamber.

bstardchild would a compression test tell you if the valve seals and or piston rings have gone.

then once you find out if its the valve seals or piston rings go abotu replacing them degreasing and rebuilding the engine. (get a haynes book it will help you)

bstardchild · Post by **bstardchild** » Thu Nov 24, 2005 2:15 pm

warrmr wrote:bstardchild would a compression test tell you if the valve seals and or piston rings have gone.

Yes and No.........

a dry test first would tell you which cyl's were low compared to the others or if all the cyls were lower than acceptable

a wet test would tell you if it's rings or valves (not valve stem seals - there is another test for this but doesn't apply to cars with cats)

Anyway

compression testing

Dry test = normal compression test throttle wide open all plugs removed and suitable compression tester in the cyl's one at a time screwed into the plug hole and nipped so the O ring seals the compression tester into the cyl....

Wet test = same as above but before you test each cylinder add 10mls of engine oil max thro the plug hole (a syringe is the best way to measure and meter the oil quantity)

If the results of the wet test are noticably higher than the results of the dry test - it's rings

if results are same or no difference it's valves that are causing the reduction in compression

Any help?