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Engine mayonaise.


Oobyscoot

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Engine Goo........

Is it normal to get a bit of engine mayonaise in these engines at this time of year?

I ask obviously because I have some. Now in my old landy, I generally get a little as soon as the damp starts, but it clears away after a few days, but this time I have rough and unpredictabe idle issues as well so its a little more of a concern. Also the coolent has dropped from the expansion tank by about 1/4 inch, it does not seem to be lacking power and is not steaming or running hot.

I am intending to get the head off next year as I want to replace the valve guides and valves, and have a good look at the bottom end (rings, bores etc).

But for the sake of a few quid and a couple hours, I dont mind changing it now if need be as well.

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not uncommon on short runs when the temp is low. Some of my cars have, others haven't. Keep an eye on the coolant level though.

It should clear up on a longer run when everything gets nice and toasty!
Also worth checking the breather system is clear.

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Check for water droplets on the dipstick. They don't always appear but an obvious indicator of blown gasket if it does. A compression test is the best way to find out, if you have two adjacent cylinders down on pressure then it's time to remove the head. I think I'd do it anyway just in case it gets worse, it's not a big job and it will give peace of mind and you might save yourself a head skim by catching it early.

Incidentally, I've had a few engines where the head gasket has failed but I've never needed to skim one yet. Try replacing the gasket first and if it  turns it needs a skim then you've only wasted the price of the gaskets and a few hours work.

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Cliftyhanger - What would you call a short run ?   I do 15 miles each way to work and back, about 11 of those miles is motorway, temp guage spends most of its life just below half. yesterday I did a run of about 35 miles M42 - M5, i would have thought that would be enough.

Firebobby - I used to loose coolant, but that was traced to a rad leak. I put a new, full width rad it it and dont think I had lost any since. I will mark the level when I get out of the office and see if it has changed when I get home after it has cooled down. The reason I wanted to do the engine next year was because I will have another car to use then so I can easily take it off the road for a few days and take my time, check everything and basically do a good job and change anything worn or broken all in one go and only have to open it up once. My only other transport at the moment are a small collection of motorbikes, it gets a bit chilly on the M5 on a bike in this weather. I will use a bike if I have to though, dont want to kill the spit.

Tom2000 - I have always gotten oil splatters on startup. The inside of my garage door is covered in the stuff.

Surely I would have thought that I would notice a loss in power if the head gasket was blown, was trundling down the M5 at 80 as normal this morning. But I am concerned that the idle speed fluctuates so much, this cant be normal can it?


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emulsified oil /moisture in the rocker area is quite normal , especially on cars with tin rocker covers, the cold air flow over the top of the engine cools it and any slight moisture content is condensed on the filler cap and inside the cover.
old ideas to help this were
fit an ally cover
lag the tin one
fit a baffle infront of the cover to deflect the cool air away
remove the fan
anyone with a overhead valve valve engine in the 60.70.80 90s would have this problem
later modern dont suffer due to more lagging ,all being OHC ,and cam box takes on the full engine temperature

dont take a head off because of a bit of salad cream  

Pete

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Lag the rocker cover?  What, like a tea cosy?

If it IS condensation, then the classic 'Italian tune-up' will help.
Take it for a drive, get the engine really hot, right through. to drive off the water that always escapes past the rings from combustion, and will condense in that cold rocker cover.   hetaing the engi e right through will evapourate it, and drive it back into the engine with through the crankcase breather.   If it reappears quickly, then be more suspicious of the gasket.

JOhn

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there was a lot of experimentation with insulated covers back in the 70s and double skin covers for noise reduction , all killed off  by OHC designs
  yes John  like a tea cosy,,      preferably with Triumph Knitted in    anything to keep the temperature Up will have an effect

     not old socks could get a bit wiffy    Pete

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I wouldn't worry about it too much. It  sounds very much like the old condensation low temp scenario. new oil can help if it hasnt been changed in a while and make sure you're running the correct thermostat to get your temp up quickly.

Is this a Spit four cylinder or a GT6 with  a later six cylinder or an early thin head six? Just a question in case it develops as the early six cylinder heads have a much lower torque and can be prone to slight head leakage, unless the centre head studs are changed for MKIIs and the head drilled to fit. Although in my experience they don't usually leak into the oil its more likely to lose compression between 3 & 4 and you would have a running problem then which you have not.

So don't worry about it a bit of emulsified oils not going to do anything detrimental.

Cheers

Darren

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Believe it or not,  I searched for "knitted rocker cover" on Google Images.

But that's crochetwork, not knitting, so completely unsuitable for a rocker cover lagging application.
Sorry, Pete, to raise your expectations!

John the Data Miner.

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I decided to pull the head in the end, as I was loosing coolant somewhere, had idle issues and was burning oil.

The inlet valve guides and valve stems are very worn so I may as well replace thoses while I am in here, the exhaust valves / guides / seats show no wear, but have previously been done for unleaded I think as it looks to be the harder valve with the bronze valve guides on the exhaust side.

I guess the inlet valves explain my oil consumption........

I am going to pull the pistons tonight and see how they and the rings are looking. The bores look very god with no detectable step or taper in the.

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Once you remove the rings don't try reusing them as you won't get them back exactly as they were, resulting in oil bypass. You will also need to glaze-bust the bores or you're unlikely to be happy with the result - I found out the hard way by rebuilding a 13/60 and despite everything being in great shape it was oily on number 1.

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Looks like an engine refresh!
Actually not a silly idea. If you are having the pistons out, well worth checking the big-ends for wear, and it is possible to swap thye mains too without removing the crank. Certainly check/replace the thrusts.

It is one of those jobs where one thing leads to another "while you are at it" ;D but for the relatively small outlay you will be getting an engine that will last a long long time.

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Sit-rep.......

Bores good, Checked them over while the pistons were out, just a bit of de-glazing is all they need.

Big end shells - just starting to wear through the white layer, some colour is showing but will be replaced. Crank journals - good, no pitting or scoring, still round, still within size  :)
Main bearings, dont look worn at all, but will be replaced for what they cost. Thrust washers - seem good, but again cheap as chips so may as well replace them.

Pistons - good, just need a clean, Little end - good, no signs of wear, no play, move freely, Piston rings - worn, thin in places, 38 thou gap in the bores, should be 8 thou. will be replaced. (still standard size).

Cylinder head will have new inlet valves / guides, new valve springs, re seat valves and a good clean.

Not as bad as it could have been. At least all the expensive bits are good. ;)

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Tom2000 wrote:
How do you go about checking the rings / removing the pistons without removing the crank? - Whilst I've got my engine out I might as well do the rest..


I've still got the block in the car, just jacked up the front end so I can get under it.

Anyhow, to pull the pistons is easy, take the head off, remove the sump, then you can undo the bolts at the bottom of the con rod, (these are strech bolts, should only be used once!) and just "poke" the pistons up and out of the top of the block. Be carefull with the big end shells, they mark easilly.

If you are planing on putting the same bits back in, keep them in order, ie. all the bits from cylinder 4 must  go back into cylinder 4.

It is not recomended to re-use piston rings once they have been pulled, however I have done it successfully in the past, just de-glaze the bores and be gentle for a couple hundred miles.


Checking the rings, firstly if you see any part of the ring is thinner than the rest - bin it. secondly put a ring into the bore it came from, use an upturned piston to poke it down about half way and level it up and then measure the gap between the ends or the ring with feeler guages. Dont know what the number should be exactly, I believ it is around 8 thou or something like, If like me, you have a gap allmost big enough to poke a finger through it - bin em.......

To be honest though, for the price of a set of rings, if you have torn down the engine that far, you may as well change em. I started off just changing a head gasket, is turning into practically a rebuild.........

:P

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2509 wrote:
I started off just changing a head gasket, is turning into practically a rebuild.........


Sames happening with me, what started with pulling the head as head gasket had blown, has turned into having the head rebuilt and converted to unleaded, now planning on taking the block out, clean & paint, new gaskets/seals and now checking for rings/thrushers etc whilst i'm their, fitting a shorter turn steering rack, fitting new suspension and fitting (hopefully) a 205 rad with header tank :/

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