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Smoky After Headgasket Change - Piston / Oil Control Rings Or Valves


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#1 baker556

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Posted 20 May 2020 - 06:48 AM

Hi all,

 

Changed the head gasket on my 1.6 1989 Miata recently, the car is very smoky on start up and driving and using excessive amounts of oil, before the head gasket replacement this wasn't a problem.

 

The head gasket changes went on well, no issues with a warped head etc. I'm wondering if I should of completed a top end rebuild with new valves or whether I should of taken the sump off, pulled the pistons out the top of the engine and replaced the oil control rings.

 

I'm reading a thread here:

https://forum.miata....t=480450&page=2

 

One of the users mentions the following, is it correct, it describes my issue but I cannot help feel it's the oil control rings instead:

 

 

Generally speaking, Rings smoke all the time. Valves smoke on hard acceleration and especially when you downshift or take your foot off the gas. Usually the exhaust guides go first, because of the heat. If you pull your plugs and they look clean, that would be another indication that the guides or seals are the culprit. Also, the oil would be much less burned running through the exhaust guides, as they would only be exposed to hot exhaust gasses, and not burned with the gas in the combustion chamber.

 

It's a bitter pill to swallow, it's probably taken 4 weeks in between work, now another issue and the head might need to come back off - or even worse a new engine.

 

Thanks,

Chris


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#2 baker556

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Posted 20 May 2020 - 06:50 AM

Just to add, the car exhaust 'pops' and 'bangs' a lot more after this HG change, have I somehow scored a valve seal somewhere along the lines letting in more air?

 

I gave the head a good clean..

 

Thanks

Chris


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#3 baker556

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Posted 20 May 2020 - 06:53 AM

Finally before anyone suggests, I've replaced the PCV valve.


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#4 carl s

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Posted 20 May 2020 - 07:44 AM

What was the reason you needed to replace the head gasket?  My car can use oil, It only does it with hard driving and I'm pretty sure from my own investigations that it's the oil control rings gummed up. A couple of flushes with 'forte advanced formula engine flush' has helped oil consumption a lot.  In theory engine flush should do very little for piston rings as not much oil gets to them in a normal engine but the NA & NB engines have oil squirters that direct oil up at the pistons from the bottom so in the MX5 case it was worth a go for my problem. Consumption went from 1.4 litre per 1000 miles down to under 0.5 litres which I'm happy to live with for now. This is in exact contradiction with your quote from Miata.net!

General wisdom of rings smoking all the time is mainly when all of them go bad, the top two can seal properly and give a good compression reading but if the third (oil scraper) ring is gummed up they will still get through oil.  Speaking to a couple of engine MX5 builders it's very common for the oil scrapers to gum up due to infrequent use and short trips, a lot more common than the valve stem oil seals to go.

 

More smoke on startup particularly after being parked overnight is a good sign of valve stem oil seals, have you done a compression test? You say the car pops and bangs do you think it is unburnt fuel could the plugs be getting oiled up causing unburnt fuel to get into the exhaust.  If it is the Valve stem oil seals there's plenty of how-to guides & videos showing how to change them without taking the head off using a special tool & rope in the cylinders.

 

I can't help thinking though it might have something to do with the reason you changed the head gasket.


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mk1 1991 Eunos with RS NB drivetrain: https://www.mx5nutz....howtopic=322586

ex - mk3 2006 2.0 sport

ex - mk2 1999 1.8is JRSC


#5 baker556

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Posted 20 May 2020 - 10:04 AM

HI Carl,

 

Reason for replacement was the car over heated but now looking back it's likely the radiator was at fault. When pulling the old gasket off everything was intact, but not an issue, the head had a clean up with all new belts fitted. The car used oil before, but I think this might have now exacerbated the issue further, however the car didn't smoke before.

 

With the head off I cleaned up the valves without removing, just the face, could this cause a problem to the seal underneath somehow, maybe some cleaning agent got underneath and dissolved the seal?? The top of the pistons were then cleaned and left overnight to soak, the levels went down only slightly but more on cyl 3 - have a feeling that maybe this cleaning agent has cause the oil ring to stick?

 

Good advice on the spark plug, I've replaced a set now as the car was running lumpy from another new set, originally thinking all of the crap from the HG residue cleaner was causing this, but now thinking it's oil on the plugs from the rings.

 

When driving the car is very smoky, but have no idea if this is headgasket cleaner still, oil or both? I've added a formula to the oil to help with potential ring issues, but more than likely this is snake oil.

 

I didn't realise you could change the valve stem seals with the head on, this makes me feel more confident - thanks for your advice, I might try the advice on miata.net with the aceton and ATF fluid down the bores to free up the rings.


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#6 carl s

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Posted 20 May 2020 - 02:26 PM

I think in some cars the engine flush can be a bit snake oil, but the US guys have some luck with soaking Seafoam through the plug holes, whereas the Forte stuff attacks it from the bottom taking advantage of the oil squirters.  How long was the engine sitting for when you fixed it? if it was months then that's enough apparently for the oil control rings to gum up.  I do feel for you as I've been through something similar and it can be frustrating chasing the cause!

 

here's the carpassionchannel guide to the oil seals:

 

https://www.youtube....h?v=Et5aJnTE5w4


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mk1 1991 Eunos with RS NB drivetrain: https://www.mx5nutz....howtopic=322586

ex - mk3 2006 2.0 sport

ex - mk2 1999 1.8is JRSC


#7 baker556

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Posted 20 May 2020 - 02:33 PM

Just watched Greg before you posted the link to YT, it doesn't look too bad.

 

I've decided to cancel my insurance for the moment, working from home anyway, whilst looking into possible fix, although it does limit testing.

 

Carl did you replace your valve steam seals? I went for a drive earlier today and it's bad to say the least smoke everywhere, oil on the dipstick has fallen significantly, therefore I do think it's the control rings being gummed up. The car sat for about 7 weeks total, I'm wondering if anything could have fallen into the chamber from the cleaning agent and caused this.

 

I'll try the product you've used with some added seafoam / acetone in the top to hopefully free them up.


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#8 carl s

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Posted 20 May 2020 - 09:08 PM

I didn't change the valve stem oil seals, it doesn't smoke on startup and the engine flush seems to have done the trick (at least so far!) to an acceptable level.  Did you have the head checked for being warped, any crankcase pressure from the dipstick?  A leakdown test would tell you more where it's coming from but the valve stem oil seals are cheap and not as hard to replace as the rings. Is it possible you could have disturbed one of the seals when the head was upturned on the bench?

 

As you say, symptoms for valve stem oil seals would be smoke on start up and on over-run when you let off the throttle from high revs or a hi-rev gear change.  They shouldn't cause smoke continuously unless badly damaged I guess.  If I had to put money on it I'd say the overheating has caused gunk that was already deposited in the oil control rings to bake and stick to the piston. I would try the seafoam / acetone soaking method a few times.  Good luck and keep us posted on how it goes  :thumb-up:  


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mk1 1991 Eunos with RS NB drivetrain: https://www.mx5nutz....howtopic=322586

ex - mk3 2006 2.0 sport

ex - mk2 1999 1.8is JRSC


#9 R3k1355

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Posted 02 June 2020 - 01:21 PM

When you did the headgasket did you skim the head and check the block?


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#10 baker556

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Posted 04 June 2020 - 03:37 PM

Didn't skim, block looked fine as did the head. Checked it with a straight edge, the HG was fine from removing after all this I think it was the rad and thermostat.

 

Still smoky.


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#11 dadbif

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Posted 04 June 2020 - 06:05 PM

Take your spark plugs out and pour some Redex into each cylinder, leave it overnight, next day put some cloths over the plug holes and crank to clear excess, replace plugs and away you go, it will be like a destroyer laying a smoke screen for a bit, but usually will free gummed up rings.
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#12 baker556

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Posted 08 June 2020 - 05:41 PM

Hi dadbif,

 

So far I've put down the plug holes, acetone, seafoam and ATF fluid, turned over slowly with a spanner, then topped up left for a few days. I've also had the compressor on each spark plug hole to force the mixture down to help clear out the rings.

 

This has been over about three weeks, yet to start her - but need to renew the insurance..

 

Plus I live in a built up area so rather drive out the way to clear the smoke screen, hopefully I'll be updating you all soon on the success, fingers crossed.


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#13 dadbif

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Posted 08 June 2020 - 05:44 PM

Hope so, crank it over with plugs out to get the worst out before you start it, put some rags over the plug holes.
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#14 carl s

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Posted 08 June 2020 - 07:38 PM

How much have you put down the bores? I'm sure it's fine but if it's litres do you need to drain the oil?


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mk1 1991 Eunos with RS NB drivetrain: https://www.mx5nutz....howtopic=322586

ex - mk3 2006 2.0 sport

ex - mk2 1999 1.8is JRSC


#15 baker556

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Posted 08 June 2020 - 09:56 PM

Carl, luckily the car is jacked up with the drain plug out and a bowl underneath to collect anything getting through.


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#16 baker556

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Posted 18 June 2020 - 08:53 AM

Update, so started the car after all the additives and still unfortunately smoky, therefore I removed all four sparkys and found all four cylinders to have oil in, hopefully these photos work:

 

IMG-20200613-161113.jpg
IMG-20200613-160857.jpg
IMG-20200613-155922.jpg
IMG-20200613-155450.jpg
IMG-20200613-154224.jpg
IMG-20200613-154216.jpg
IMG-20200613-154157.jpg
IMG-20200613-154136.jpg

 

I find it strange that all four either valve stems or oil control rings have gone? I read somewhere that fitting a new HG causes higher compression so anything weak in the chain will be more likely to fail. I'm still undecided whether this is rings or valve stem seals, loads of mx5 owners have oil ring issues unfortunately pointing that way :(


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#17 baker556

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Posted 18 June 2020 - 09:02 AM

Here's a video of a quick idle, showing the amount of smoke...this was never an issue before the HG.

 


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#18 R3k1355

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Posted 18 June 2020 - 05:09 PM

Stem seals are also a problem, what with the age of Mk1's.

 

You can do the valve stem seals in-situ, probs best to start there.


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#19 baker556

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Posted 18 June 2020 - 07:38 PM

Hi R3k1355

 

I'm thinking the same just spent so much time fixing this up, almost think is it worth keeping putting time and money or get a new engine.

 

Cheers


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#20 dadbif

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Posted 18 June 2020 - 09:33 PM

Had you completely cleared all the additives out, used to take few minutes to clear it all
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