Discussion
The oil control rings are the bottom sealing ring on the pistons. Mx5 mk1 and mk2 have a habit of gumming them up if not well maintained and fed good oil. The result is that when cold the vacuum above the piston draws oil up and burns it. It's a full engine strip down, new rings which may or may not require a rebore and pistons too depending on the wear on the cylinders. You are looking at 1000-1500 quid or a second hand engine. When selling a smokey MX5 anyone who knows them will tell you it's the valve guides as the symptoms are almost identical but MX5s are not noted for valve guide and valve stem oil seal problems. In short, walk away. The guides and seals will run you £500 + in parts and labour and when they don't fix you will then fork out for the engine rebuild too.
roddo said:
Mk2's suffer from oil control rings
As did my Mk1 at only 80,000 miles. Fixed now (after lots of useful advice from roddo) but time consuming and expensive.http://www.mx5nutz.com/forum/index.php?showtopic=1...
Edited by ronime on Friday 26th July 23:30
well ive gone against everyones advice and just bought the car.been told to do a compression check to see what the problem is.been told to do it then check numbers then pour a bit of oil down plug holes then do it again.and this will tell me if its piston rings or valve stem seals. is this right and how does this tell me whats what
Sounds about right. Adding the oil should temporarily block any gaps around the rings. So if you have low compression both with and without the oil then the issue is at the top of the engine (valves) whereas if you have low compression before you add the oil and higher compression after then the oil plugged the gap in the rings and they are the culprit.
Good luck with the project. I also recently bought myself a rather battered Mk2 which I am renovating.
Good luck with the project. I also recently bought myself a rather battered Mk2 which I am renovating.
ronime said:
Remove the head, fit new valve seals and replace. If it cures the oil consumption problem then you don't need to strip the block and replace the piston rings.
Isn't it bit of a pig to do. Would be a lot easier to buy a cheap engine and take the head off and replace. Been offered one for 200 chasdad said:
ronime said:
Remove the head, fit new valve seals and replace. If it cures the oil consumption problem then you don't need to strip the block and replace the piston rings.
Isn't it bit of a pig to do. Would be a lot easier to buy a cheap engine and take the head off and replace. Been offered one for 200 fatjon said:
Good luck. As has been said earlier oil control rings have zero effect on compression. A compression test will not detect the problem with them. Hope you get lucky and it's the valve side of things but I would give that a 1 in 10 chance.
I think your right. Don't think I'm going to bother . Think I'm going to try and find a cheap engine and have a go at it myselfIf there is a "problem with oil control rings gumming up" - I've no idea as I've no experience of MX5s - you might get lucky with a treatment of Redex or similar. Basically just warm the engine, a spoonful of Redex into one cylinder, leave for a bit and take for a run - I warn you it will probably smoke like a beagle as it will burn all the carbon out of the cylinder and all the crap off the valves. You'll either lose even more compression as the worn engine loses all the carbon that was sealing it or, if you are the lucky type it may just un gum the control rings and sort the problem - either way if you have already decided on an engine change what have you to lose?
I've had both results in the past - a Reliant that lost practically all compression and a Yamaha 750 that had been laid up and the rings had stuck was as good as new.
I've had both results in the past - a Reliant that lost practically all compression and a Yamaha 750 that had been laid up and the rings had stuck was as good as new.
spoodler said:
If there is a "problem with oil control rings gumming up" - I've no idea as I've no experience of MX5s - you might get lucky with a treatment of Redex or similar. Basically just warm the engine, a spoonful of Redex into one cylinder, leave for a bit and take for a run - I warn you it will probably smoke like a beagle as it will burn all the carbon out of the cylinder and all the crap off the valves. You'll either lose even more compression as the worn engine loses all the carbon that was sealing it or, if you are the lucky type it may just un gum the control rings and sort the problem - either way if you have already decided on an engine change what have you to lose?
I've had both results in the past - a Reliant that lost practically all compression and a Yamaha 750 that had been laid up and the rings had stuck was as good as new.
Thanks ill give it a try .Do you mean take just one plug out and a spoonful of redex down the hole or do it to all four.I've had both results in the past - a Reliant that lost practically all compression and a Yamaha 750 that had been laid up and the rings had stuck was as good as new.
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