Have my valve stem seals gone?
Discussion
As above wondering if my valve stem seals have gone / going. On start up there isn't any oily smoke but on wot in 2nd and 3rd you do tend to get some blue smoke out of the back and even more so when you snap the throttle shut, particularly in 5th. I bought the car cheaply knowing about this and I've owned the car for about 15 months and it's never deteriorated, but then last year I only covered 300 miles.
Engine temp also seems to play a part and the engine is a bit rattley until the oil gets round after first starting. The engine still pulls nice and strongly so I wasn't suspecting ring failure. I've got a spare engine (short nose as apposed to the long nose that's in there now) which I bought a while back so wondered if it would be worth putting the whole thing in or just swapping the heads over?
Cheers,
Matt.
Engine temp also seems to play a part and the engine is a bit rattley until the oil gets round after first starting. The engine still pulls nice and strongly so I wasn't suspecting ring failure. I've got a spare engine (short nose as apposed to the long nose that's in there now) which I bought a while back so wondered if it would be worth putting the whole thing in or just swapping the heads over?
Cheers,
Matt.
Sounds like valve stem seals to me.
I would keep an eye on the oil level. If your lazy like me, a bottle of "stop smoke" the has been good temporary bodge. Also tells me that the valve stem seals are f
ked. My car had been lying for 2 years so I suspect the seals have hardened.
Yeah, just swap the heads over.
I would keep an eye on the oil level. If your lazy like me, a bottle of "stop smoke" the has been good temporary bodge. Also tells me that the valve stem seals are f
ked. My car had been lying for 2 years so I suspect the seals have hardened. Yeah, just swap the heads over.
Oil control rings losing tension are a known issue with Mazda engines.
Just rebuilt my 1992 1.6 engine. The (original) valve stem seals had more than enough elasticity but the oil control rings had failed.
If you are having to top up after only 25 miles then you probably have an oil ring problem. I was using a litre of oil every 400 miles or less.
Just rebuilt my 1992 1.6 engine. The (original) valve stem seals had more than enough elasticity but the oil control rings had failed.
If you are having to top up after only 25 miles then you probably have an oil ring problem. I was using a litre of oil every 400 miles or less.
Yes, they are the (3rd) rings at the bottom of the piston. Top and second rings on my engine were fine at 80,000 miles but the oil control rings had clearly lost tension.
Rolling road tests on the same dyno a year apart showed that the engine was still pulling 120hp even after it started smoking. If you can live with the oil top up regime then just soldier on but for me the smell of burning oil spoiled the whole top-down experience.
Rolling road tests on the same dyno a year apart showed that the engine was still pulling 120hp even after it started smoking. If you can live with the oil top up regime then just soldier on but for me the smell of burning oil spoiled the whole top-down experience.
Edited by ronime on Thursday 28th March 23:38
The intial symptoms may lead you towards valve guides and valve stem oil seals but that is not too likely. Having rebuilt a couple it's not so much losing tension on the oil scraper ring as it getting so gummed up in the slot that it can't move at all. Once the pistons are out it's easy enough to take the ring out and clean up the groove and then it's fine. A bit of a false economy though unless the bores and rings are perfect. I have always gone for new rings and a deglaze of the bores. I think it is blow by from worn compression rings that scorches the oil around the control ring and gums it into its groove with burned carbon.
Seems to be more of a problem on later engines BTW, 99 onwards mainly though not exclusively.
Eventually the vacuum at idle and on the over run is enough to suck up the oil that not's not being scraped off the cylinder walls right past the compression rings and into the combustion chambers then it really starts to smoke!
Seems to be more of a problem on later engines BTW, 99 onwards mainly though not exclusively.
Eventually the vacuum at idle and on the over run is enough to suck up the oil that not's not being scraped off the cylinder walls right past the compression rings and into the combustion chambers then it really starts to smoke!
Could anyone give an indication of the cost of fixing this issue? My car has what appears to be exactly the same issue. I'm not afraid of attempting reasonably big jobs myself but changing piston rings sounds fairly in depth ! I'm presuming this wouldn't be a cheap fix at a garage though?
If you're changing the rings you might as well change the shells / bearings at the same time, so you looking at £200 - £300 in parts before you add on the labour I'd have thought. Especially if you refresh the head with new stem seals at the same point. Don't forget you'll need a gasket set and new head bolts. Labour would probably be 1.5 days worth. Although involved (engine out) its a job I have done before on other cars.
A cheaper and quicker option is to buy a replacement engine. These can be had for £100 upwards. I paid £120 for engine and gearbox with all anciliaries. Just wanted to avoid the engine out if I could.
A cheaper and quicker option is to buy a replacement engine. These can be had for £100 upwards. I paid £120 for engine and gearbox with all anciliaries. Just wanted to avoid the engine out if I could.
fatjon said:
Having rebuilt a couple it's not so much losing tension on the oil scraper ring as it getting so gummed up in the slot that it can't move at all. Once the pistons are out it's easy enough to take the ring out and clean up the groove and then it's fine.
My rings were not gummed up:
Old oil control rings had much less tension than new ones (new rings on the top row):
Edited by ronime on Saturday 6th April 22:43
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