white smoke after 1275 engine build

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ampwhu
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white smoke after 1275 engine build

Post by ampwhu »

i am after so advice as i am unsure of where to look next. i rebuilt my 1275 back over the winter. I ran it for the 1st time yesterday.

I used graphite build paste on the rebuild. When i first did an oil pressure check on the engine with the plugs out, I span the engine over on the starter to circulate oil and get pressure. I saw a reading of 80/90psi at first. I didn't worry because i thought it was the paste causing this.

when i ran the engine at first yesterday, the pressure reached around 100psi, but the engine ran lovely at on first start up. gradually the pressure started to reduce. at first, the only smoke coming out the exhaust, was normal as you would expect.

As the engine was being lightly tuned by strobe, tickover and mixture, it started to smoke quite badly with white smoke. At this point the front timing cover started to leak (alloy cover with rubber seal if you remember). Once the engine was up to temp on the cooling circuit etc, the oil pressure sat at 30psi and the engine idled lovely. I set the tickover on a little fast (maybe 1500rpm). i then turned the engine off to take a look.

I removed the plugs one by one (to check colour to see where the mixture was) and number 4 plug was covered in oil. The other 3 weren't. I shined a light down the plug hole and the top of the piston was clean (all new pistons). i cleaned all the plugs and fitted them.

I went around the the back exhaust pipe and there were a couple of small oil patches on the floor. Looking inside the tail pipe and there was a small amount of oil in there. I'm unsure of where to look now.

There has been no coolant loss. I have a PCV valve fitted to the inlet manifold which is connected to the timing chain cover.

could i have some advice please?
oliver90owner
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Re: white smoke after 1275 engine build

Post by oliver90owner »

Initial thoughts:

Is the oil leak caused by excessive crankcase pressure?

Number 4 oil looks dodgy. Rings fitted upside down? Excessive gap between ring and piston? Oil control ring not working. Excessive blow-by due to oval bores? Oil pouring down a valve stem/guide?

I would expect blue smoke from oil.

Not knowing the history of the rebuild means I have no particular clues to start with. Back in your court.
paul 300358
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Re: white smoke after 1275 engine build

Post by paul 300358 »

Have a look at the oil pressure relief valve. the oil pressure should never be over about 65 psi. Also, if you had it rebored, did you clean out the oilways?
ampwhu
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Re: white smoke after 1275 engine build

Post by ampwhu »

i had the block relined back to standard 70.61mm. the bores were honed. There are new pistons and rings fitted also.

i would agree that blue smoke would be rings. But this is white smoke that smells like oil. It's rather bad.

excessive crankcase pressure? Would the PCV not help that? There was a small amount of smoke coming from the rocker cover filter also, but minimal. I would expect some smoke from a newly built engine, but not this.

would you advise a compression test on cylinder 4?
ampwhu
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Re: white smoke after 1275 engine build

Post by ampwhu »

paul 300358 wrote: Sun Apr 11, 2021 9:08 am Have a look at the oil pressure relief valve. the oil pressure should never be over about 65 psi. Also, if you had it rebored, did you clean out the oilways?
yes. I had the plugs removed and had NPT plugs fitted. I cleaned the oilways with gun cleaner then compressed air. I did this around 6 times. They were clean.
pgp001
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Re: white smoke after 1275 engine build

Post by pgp001 »

Not on the Morris but............

When I see a load of white oily smelling smoke from the exhaust of my BSA Gold Star, it means that with standing for months the oil has got past the non return valve and collected in the crankcase, it must slosh around and get back up the bore past the rings on the down stroke.
Once it all gets pumped back to the tank the smoke clears.

So on your Morris engine I would suspect something similar on cylinder 4, in that there is excessive oil finding its way either past the rings, or down a valve guide. The fact that it is white and not blue probably means that most of it is being atomised and emitted without actually being burnt a bit like when an injector goes bad on a diesel engine.

Your 100 PSI oil pressure sounds very wrong to me as well.
Why not try a compression test first job and see if that gives any more clues, It does sound as though the head might be coming off for some investigation.

Sorry I cannot be of more help.
Phil P
paul 300358
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Re: white smoke after 1275 engine build

Post by paul 300358 »

What sort of pressure relive valve have you fitted and is the spring the standard length?
ampwhu
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Re: white smoke after 1275 engine build

Post by ampwhu »

It was the standard 1275 one. When I get a chance this week, I'll check it and its length.

When the engine had warmed fully, it was showing at 30psi so I dont think it's an issue now. I'll still check.
MCYorks
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Re: white smoke after 1275 engine build

Post by MCYorks »

ampwhu wrote: Sun Apr 11, 2021 7:01 am when i ran the engine at first yesterday, the pressure reached around 100psi
That's certainly too high. I've never had more than 70psi even when starting on sub-zero mornings! Do you know if the oil pressure gauge actually reads correctly? Unless it's been calibrated, then there's no guarantee it's correct. If you have another pressure gauge then you could compare the two.
ampwhu
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Re: white smoke after 1275 engine build

Post by ampwhu »

Oil pressure gauge was connected to the 1098 I removed so it was working correctly. The 1098 used to show 60psi on start up
MCYorks
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Re: white smoke after 1275 engine build

Post by MCYorks »

ampwhu wrote: Sun Apr 11, 2021 6:09 pm Oil pressure gauge was connected to the 1098 I removed so it was working correctly. The 1098 used to show 60psi on start up
Sounds positive. In that case I'd be going with paul300358's suggestion and checking the relief valve. At least high oil pressure is easier to fix than low oil pressure :D
ampwhu
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Re: white smoke after 1275 engine build

Post by ampwhu »

I think that's the easy issue. I dont know if that's the cause of the white smoke.

My plan is to remove the manifold this week to see which cylinder the oil is coming from and then remove the head. Hopefully that might give me an answer
oliver90owner
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Re: white smoke after 1275 engine build

Post by oliver90owner »

I removed the plugs one by one (to check colour to see where the mixture was) and number 4 plug was covered in oil.

If that was the plug electrodes and not outside the engine (valve cover leak), there seems little doubt as to which pot is the problem?
ampwhu
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Re: white smoke after 1275 engine build

Post by ampwhu »

yes it was the electrode. this week (if i find the time) i will strip the engine and report what i find.

my main concearn is the high oil pressure at the start and what damage it has done. before i switched it off, it was idling at 30psi. So maybe a blockage that has cleared itself? I did use Graphogan paste, which i think could have been an issue and i am now telling myself that was a mistake.

I will find out in due course and will require further advice.
ampwhu
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Re: white smoke after 1275 engine build

Post by ampwhu »

Ok, I've removed the inlet manifold and there is oil in it. Also oil in the cylinder head inlet ports.

My theory is the pcv valve is sucking oil from timing cover and sending it straight to the inlet manifold. This is going into the cylinder bore and that's why I have white smoke. I'm also thinking that the 100psi oil pressure would have something to do with this. I know its running at 30psi when I switched it off, but would it still be burning all that oil?

Do I now do a compression test to see if valves and piston rings are ok?
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Re: white smoke after 1275 engine build

Post by pgp001 »

Have you checked inside the PCV valve and hoses to see if they are really oily ?
If they are, then you may be on to something, if not then you can probably discount that idea.

I am curious to know why your new alloy timing cover seal failed as well, that is a bit disappointing for you.

Phil P
ampwhu
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Re: white smoke after 1275 engine build

Post by ampwhu »

I think the reason it failed was probably the crankcase pressure/oil pressure. I've purchased a new seal set which arrived today. It was a heavy leak at the bottom. I'll renew the circular oil seal as well.
paul 300358
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Re: white smoke after 1275 engine build

Post by paul 300358 »

This is probably a daft suggestion, but are you sure that the dip stick is the correct length? I seem to remember there was a couple of different lengths for different A series engines.

I may have dreamt it!!!!
ampwhu
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Re: white smoke after 1275 engine build

Post by ampwhu »

What makes you ask that? Too much oil?

Moss catalogue lists 1098 and 1275 as the same part number. 12G175. I just looked.
paul 300358
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Re: white smoke after 1275 engine build

Post by paul 300358 »

I'm pretty sure that the 803cc/948cc engine oil dip stick is a different length than the 1098cc/1275cc. If you put too much oil in, it would smoke.
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