Hi, Apologies in advance for the rather long post and thanks for the help and info (by email) from Mazda Mender. I wonder if anyone can help with my frustrating problem. I have recently purchased a non running Eunos auto that had been cooked due to a split heater hose. I had the head skimmed, valve seats recut, valves lapped and valves and springs assembled with new valve stem seals (non Mazda) by a very reputable engineering firm in Carmarthen. Having reassembled everything I now have horrendous whitish blue smoke on start up.This takes about 15 secs to appear and is like a fog behind the car and lasts for about 10 mins at tickover (with blipping the throttle). If you turn the engine off after a couple of mins and remove the plugs you can actually see the oil on top of the pistons. I have cleaned this oil out with petrol and a wet and dry vacuum cleaner, Made sure that at least one inlet and one exhaust valve is open and left overnight. Next morning there is no oil in the bores until I start up when it smokes all over again. If driven after the smoke has cleared then all is fine. Compression pressures are reasonable for a 150k mls car and if the oil control ring are naff I would expect it to smoke all the time. I have also removed the tube from the inlet manifold to the vacuun modulator valve in the auto box in case that was faulty and sucking up transmission fluid (thanks Mazder mender) and ditto the servo pipe. I’m now stuck and tearing my hair out and I can’t afford to do that at my age. Can anyone throw any more light on this problem. All suggestions will be welcome.
Regards Harvey
Hi Harvey,
Wrong or wrongly fitted valve stem seals might be a reason but it does sound like a lot of oil doesn’t it.
Have you actually ran it on the roads a while? Thoughts are the rings may have stuck due to water down the bores if the head gasket went. A bit of running might free it. Maybe an engine oil flush too, or get it warm and put a few teaspoons of Redex down the plug holes and leave to soak, used to be a favourite trick.
Hi Rich M. Yes I’ve driven it about 60 mls in total. The last one was a run of about 45 mls and it got quite a blast too. Compression pressure figures are reasonable so I wouldn’t expect ring problems but if it was I would expect oil burning all the time not just on start up. I did put fresh oil in after the rebuild but not flushing oil. Maybe that’s the next job.
Note to all who respond to this problem. If my response to any suggestions appears negative or argumentative it’s not meant to be. So apologies in advance. It’s just that I’.m getting so frustrated !
Harvey
It does sound to me like valve stem oil seals…
Hi Harvey, No probs, just going through ideas hoping it isn’t the valve stem seals. What about the PCV, may be worth changing for what they cost, and check the restrictor is in the tube.
Hi Victormeldrew and Rich. I wouldn’t actually mind now if it was definately valve stem seals - at least I would know! I have tried sucking and blowing through the PCV and it only works in the right direction. I think at some stage (I’ve done so many test I’m losing count and my marbles)I tried running it with the oil filler cap removed - therefore no pressure build up. It was still smokey though.
Harvey
Then that really only leaves the seals, or maybe the head gasket at a push. Have you done a full leak-down test of the compression? And when you say ‘good compression for its age’ - I take that to mean ‘not particularly great’ compression?
Hi both, yes agreed and you clearly know what you’re on with Harvey. We can only explore the possibilities before pulling the head, followed by pistons if the valve seals are ok. We know it’s usually oil being pumped up worn bores or past stuck rings, or draining down valve stems past the seals. The strange thing is how long it takes to clear. I’d have thought stem seals would’ve cleared after a few seconds. So maybe the oil is coming up the bores and the time relates to the pistons heating and expanding to seal better.
The PCV might give a clue. It is hard to check off the car as it has a spring and shaped parts which cause a balancing act of open/close depending on pressure on both sides of the valve. There should be a small negative pressure in the crankcase during idling which would indicate little piston blow by and tend to keep oil in the crankcase rather than causing it to be pushed up the bores. Worth a quick check; during idle, remove the oil filler cap and hold your palm over the hole. It should be sucked in gently. If the suction is great it suggests the PCV is stuck wide open, if there is no suction or your hand is pushed away it suggests excess blow by or PCV stuck closed.
Hi, Yes it is looking more and more like the seals. The head gasket was obviously new and was a good one. (ADL/Blueprint) . Compression figures are all around 170psi. How do I do a leak down test.
Cheers
Harvey
You could try a proper leak down test Harvey but with those compression figures I wouldn’t expect it to tell you much and certainly it won’t tell if the oil rings or stem seals are the oil problem. Check for crankcase pressure during idling first which might indicate blow by.
What about after putting a little oil in the cylinders?
Hi Jon, no need to put oil in the cylinders - it’s there already! lol. Seriously though- yes oil in the cylinders puts the compression pressures up to about 185psi indicating worn rings, but it’s strange that there is no evidence of serious oil burning when warm. Also would that allow so much oil to get into the cylinders so quickly?
Harvey
Hi Rich. I’ll try to check for crankcase pressure tomorrow. With a breather from the camcover to the inlet manifold and one feeding the throttle body, would there be any crankcase pressure or would it be sucked into the engine?
Harvey
Hi Rich, Sorry, in my haste I scrolled down passed your note. I will try what you suggest to check the PCV valve and crankcase pressure/ suction. I’ll keep you all posted.
Harvey
That amount of pressure difference is beyond tolerance, and so suggests there’s something going on down in the bores… With the oil in, it’s close enough to suggest the head is ok.
Oh dear, it’s beginning to look like rings and/or bores. If it does prove to be sticky rings rather than very worn or broken ones is there anything that can be put in either the bores or the oil to free them up. Does Redex still work?
Harvey
Something like Wynn’s Engine Flush would be better for that job…
Hi, the net effect should still be a slightly lower pressure when felt at the oil fill hole during idle.
Just had a look at the compression test figs and Haynes gives
1.6
192 standard 135 minimum
1.8
182 standard 128 min
with a max variation between cyls of 28
That’s for minimum 7 compression strokes with good batt and throttle fully open. So yours all around 170 look good though the wet check suggests maybe a bit of bore wear.
A leakdown test is more useful if you have one or 2 cyls very different from the others. Like a compression test it is confined to checking between compression rings and valve seats so wont show duff oil control rings or valve stem seals. The cyl is filled with compressed air and then gives a chance to find the rate of loss for each cyl and by listening/inspecting where it’s being lost so might find a head gasket loss or valve instead of bore problem for example. That probably wouldn’t help with your oil problem with all cyls showing equal compression.
So we keep coming back to checking for excess blow by cold/hot indicating worn bores, stuck oil control rings, or the valve stem seals. Jon’s suggestion of Wynns flush through the plug holes looks good. I’m not sure you can still get the old Redex and, having used them both, the Wynns flush is thinner so would penetrate better and won’t do any harm when it drops into the sump. I’d expect it to be better at removing deposits too and perhaps best put in a warm engine and left a few hours. Do spin it over with the plugs out and cloths over the plug holes to expell excess before trying to restart. (Fit the sparkplugs to the leads and rest on the head or unplug the coilpack to avoid stressing the coil, and bear in mind fuel will still be pumped into the inlets unless you disable the injection.)
Morning all. Just removed the oil filler cap with the engine on tickover (slightly fast) and have very noticeable pressure there. If I move my hand away about 1 -2 inches I can still feel it blowing. Should I try an new PCV valve before I shoot myself?
Cheers Harvey