I have an MX6, which occassionally (too many double letters there) judders at around 2k revs. I asked the my local independent garage what could be causing it, they scratched their heads and said it could be any number of things. I thought it could be the plugs, as I use NGK and not the mazda ones. I was going to try them at the next service. Yesterday I gave a friend of mine a lift in it, and he immediately asked is it meant to do that?
I said no. He replied that his mondeo used to do that, and it was something to do with the valves (probably a bit sticky) and it was an expensive head off job. (even more so, because this car has 24 of them).
Could this be the case? I will also check with my local garage to see what they think. The other question is, as it has been happening on and off for over a year, will it damage the car, if i dont get it done, not straight away at least? Anything over £250 will have to wait a month or two anyway.
Many Thanks
Jonathan
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If it is sticking valves, then yes, a long period of operation could have caused damge in the form of burned out valve seats. However, try the plug change now - no need to wait for service time.
If not sucessful then an oil change, a can of fuel system cleaner and an Italian tune up may help to free up the valves.
Regards
John
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Will do
I give it an "italian" every day :-)
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Ill wager if it is not elecrical then you will need a head rebuild.
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I remember when these were new and some magazine (perfomance car maybe) was running one of these as a long term test they had to have all the hydraulic tappets replaced after a few months. I think there were a number of readers who wrote in with similar problems. Sounds like the same thing you have.
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Johnathan,
I think you will find that the original fitment "Mazda" plugs are in fact made by NGK, so should not make a difference, unless they are due for changing anyway. May be wrong as they sometimes use Nippon-Denso, but in my humble opinion NGK are superior to N-D !!
Other suggestiona all sound, but I would suggest a Forte Gas Treatment as well as an injector cleaner - this product is designed specifically to remove carbon deposits from valve stems etc.
Regards, Adam
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are these treatments safe with a cat?
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Absolutely !
Regards, Adam
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Hmm, you may remember me writing in with a similar problem on my dads Mondeo. The car seemed to die for a split second. We are now suspecting valves, after changing all sorts of things.
Could oil make a differance, we use 10/30 which is considered thick, could it be gumming up the ports?
Kev
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If it's a Zetec, then anything thicker than a 10-30 could cause problems, but if you've been using a decent 10-30 oil and changing it regularly it should be OK. That's why I suggested an oil change in this case - the problem could be due to gummed up hydraulic tappets.
regards
john
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in my experience, gummed up hydraulic tappets are accompanied by tappet noise. There was an earlier discussion about this. Given the intermittent nature and the engine speed (2000) I would suspect fuel or ignition. Maybe an injector problem but you could not rule out a faulty sensor feeding the ECU with incorrect data and causing it to make an unsuitable adjustment to ignition or fuel setting. Have you had it checked on an engine analyzer by a tuning specialist?
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Not yet
I also spoke to a friendly mechanic, who said that it is unlikely to be a valve prob, because they either work or don't, so it wouldn't matter at what speed the engine is.
I will swap the plugs for mazda ones this weekend and see if that makes a difference.
I will also try those engine lotions. Any brands that people can recommend?????
Many Thanks
Jonathan
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The specification of oil used in some engines can have a profound effect upon engine starting and performance.
A favourite of mine was a Vauxhall Astra that refused to start on occaisions and idled roughly. A flushing oil and the proper 10/30 oil and all was restored.
Don't overlook the obvious.
Forte and Wynn's produce proffesional-use-only engine additives - these can work to great effect. But, in my experience, a good old head strip down and rebuild (usually using stepped valves in place of the standard parralell stems) is the only cure for valve sticking.
I don't think your friendly mechanic has experienced this sticking valve syndrome. This can cause the valve(s) to partially stick at a certain temperature and cause misfires and lack of power.
When Rover had this problem back along with their T and K series engines, I could identify it by driving from cold and stopping in a layby 2 miles away. If the valves were gummed up, the engine would misfire in this layby. It was all temperature related. We found, upon investigation, that many of these engines were suffering from thermostat failure, causing cool running and extended warm-up cycles. This just accellerated the gum/lacquer build-up.
We havn't seen any further valve sticking problems since introduction of these 'carbon break' exhaust valves.
Shame, really, this was a constant source of work for us......
Rgds
David
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I think John Slaughter previously pointed out that Ford dealer bulk oil is actually Texaco Havoline 5w-30 semi syntheticwhich is one of the best semi synthatics around. But the other little problem with Mondeos is they tend to need a new set of leads every 3 years or so. Cheap at £30 or so because they're short leads.
HJ
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