16 replies to this topic

[sixtyeight]

So have a bit of a smoking problem... some background

 

1275cc pre A+ block

12G940 head

HIF44 carb

engine done unknown kms. rebuilt late 1990s. I'd estimate 50,000km

 

Engine removed from car ~4 years ago, was running fine.

Removed head ~3 years ago to give it a once over- new valve stem seals, decoke, re-lap valves, new head gasket (payen BK450) and stud kit (http://minispares.co...c/C-AHT280.aspx and http://minispares.co...s/C-AHT281.aspx)

 

cleaned the bores/piston crowns while head was off (now realise this shouldn't have been done).

 

reassembled, torqued head stud nuts up to 65lb/ft as per minispares link, with oil. Then I read here http://minispares.co...-nut-washer-kit that 45lb/ft is recommended for rover/payen.

 

Penrite HPR-30 oil in the engine

 

prior to first start I reverse primed the oil pump and squirted some oil into the combustion chambers.

 

smokes fairly badly once warmed up - car isn't registered so can't be driven, so all tests done while stationary. Smokes mostly on throttle, not over run. otherwise ran fantastically. oil pressure 75 psi cold, 50 psi @ idle when hot. 

 

there was some bubbling under the 5/16 ARP head bolt. the thread does not go through the head into a water gallery.

 

removed rocker cover cap and some blue smoke visible chuffing out.

 

only has one breather on transfer case. tested with breather to atmosphere and fed to carby, no change.

 

prior to headgasket/head work, engine never smoked.

 

so.....

 

ripped the head off

 

photo time.

 

 

 

 

 

 

 

 

 

 

 

plenty of oil under on the surfaces of the head gasket on the pushrod side of the engine.

lots of oil in the inlet ports

bores look good, no lip at top of bore.

barely any movement of piston in bore at TDC, BDC, or middle of travel.

there was a ~1.5cm diameter pool of oil on each piston when I removed the head. no photo sorry!

 

compression test prior to removing head was 150 on #1, 190-200psi on #2-#4. #1 came up to 170 after squirting some oil in the chamber.

 

Praying it's not rings (all four to go at once???), and looking at the head gasket oil hoping that it was over tightened and warped? possible? 

 

I think first test will be new gasket/head studs etc, and retorque up to 45lb/ft, and retest, before stripping engine!

 

Any input thoughts from people many tims more knowledgable than myself?

 

 

[Cooperman]

You could re-assemble it, using the correct head nut torque and using a BK450 head gasket. Do not put any oil onto the gasket, as you would do with a copper-faced gasket, just fit it dry.

Change to a 20w50 mineral oil.

Make sure the breathers are not blocked.

Start it and put it on the road. Then do about 150 miles and re-torque the head studs by undoing each one by 1/2 a turn and re-torquing in the correct sequence.

Re-set the valve clearances and check the mixture settings to ensure it is not running too rich.

Check the ignition timing.

Drive the car for around another 500 miles and see how it goes and if it stops smoking.

[sixtyeight]

cheers.. the oil is fresh 20w 60 mineral penrite.. it's their replacement for 20w 50, it has an 'extra ten' haha - marketing speak. I think it's a 20w50 really. It's high zinc (1500ppm) and there blurb states it is for minis . it's pretty much the same as the penrite classic mini oil. http://www.penriteoi...p?id_products=4

 

unfortunately I can't drive it - it's not registered, and smoking like this it won't be able to be registered!

 

but yeh, plan is to reassemble and retest..

Edited by sixtyeight, 29 January 2017 - 12:26 AM.

[sixtyeight]

am I right in thinking that those head studs are now scrap? just working out what to buy for reinstalling the head.

[Spider]

Tim,

 

Used engines don't store too well. Also, looking at your bores, they are worn. It could have been from a bit of over fueling?  But, none the less, pretty clear, you can see where all the rings reach at the top of the stroke, there's no visible honing marks and there's even some scoring, while visible, isn't the end of the world.

 

Having previously torqued the head up to 65 ft / lb, the block deck will not likely be flat, rub it a few times with an Oil Stone to see.

 

In regards to the head studs, measure the diameter of them in 3 place, where the threads end, and in the centre. Any thinning and yes, they have been taken past their point of yield and are good for other purposes.

[sixtyeight]

cheers.. the photos look much worse than in normal light - the flash seems to have shown much more than the naked eye sees. 

 

yeh the engine has sat unused twice now... once by previous owner for several years, and now by me, so I know it's asking a lot of it! Will reassemble, test, and if no good, take it for a rebore and hone. oil pressure is great on it, so shouldn't have to touch bearings etc.

[sixtyeight]

some more photos with no flash

 

1

 

2

 

3

 

4

 

not of the small vertical marks can be detected with finger nail.

[Spider]

OK cheers.

 

Does look much better in those photos.

 

Not much to loose by trying an oil change - try some Diesel Engine oil for a short while when you get it on the road, say 300 - 500 km. That will give it all a good flush. Then go over to something like Penrite's HPR 30.

 

Check the block deck though for flatness before you go too far.

 

Also, remove the top one or two threads from all the head stud holes, they'll well and truly be pulled up like a volcano now!

 

<Edit: What's 850man had to say on it? >

Edited by Moke Spider, 29 January 2017 - 01:14 AM.

[Magneto]

I think you have some stuck rings, from sitting....you could try pouring some diesel fuel in the cylinders and let it set for a few days, then wipe that out and put it back together and see what happens.

 

Make sure the head doesn't have a crack in it somewhere - look very carefully.

[sixtyeight]

block and head are flat but only testing using a 30cm stainless rule and a .06mm feeler.

[Spider]

block and head are flat but only testing using a 30cm stainless rule and a .06mm feeler.

 

Give it a couple of wipes over with an Oil Stone, that'll show up everything much better.

[ACDodd]

Rich running and glazed bores.

Ac

[sledgehammer]

I'm also wondering if the rings (oil control) are gummed up / weak

 

or what is more likely , the oil drain holes behind the oil control ring is blocked / restricted

 

another (less likely) possibility , worn lands on the pistons letting the rings move up/down , that can pump oil up as well

 

what ever you do - remember the exhaust will have a fair bit of oil in it - so won't stop smoking as soon as problem sorted

 

as above diesel can loosen the gummed rings sometimes , I sometimes fire an air line around the ring area after -

 

but put a rag over the area - or you will get a face full

 

as above bores do look glazed 

Edited by sledgehammer, 29 January 2017 - 12:23 PM.

[sixtyeight]

thanks all, very muchly appreciated!

 

Have ordered bits, will strip down the head on the weekend, check valve guides and seals - will replace the seals again as the current ones while new, did sit unused on the head for over 2 years... 

 

new studs/gasket

 

will drain the oil, soak the pistons/bores in ATF/acetone mix (been reading about freeing up stuck rings - seems to be the most recommended method)... give them a blast with the air hose...

 

I think that is giving it's best chance at being less smokey for the time being. if this fails, it will be engine out and rebore/hone/pistons and rings.

 

whats the clearance on valves to valve guides? surely if I need new guides I'll need new valves too?

[sixtyeight]

just thought I'd give this a mid-way through update...

 

Pre soaking, pistons could barely be moved in the bores fore and aft. 

 

Been soaking the pistons/bores in ATF/acetone mix. 

 

At first, 2 and 3 would drain quicker than 1 and 4. Would drip at a rate of about 1 drop per 2 seconds out of the sump. Could see tiny bubbles form around the edge of the fluid where it was draining past the rings on all pistons. After letting the ATF drain through, all pistons were left with a nice deposit of carbon on top. 

 

Rinse and repeat several times (have run around 4l of ATF/acetone through it now!).

 

Currently the mix is dripping through at around 1 drop every 6 seconds, so rings are sealing better. Each cylinder drains at an approximate equal rate.

 

I can move the pistons fore and aft in the bores a bit more easily, and it squeezes residual fluid back up so there is fluid between the rings and piston. Carbon crud has stopped rising to the top and sitting on the piston crowns after the fluid has drained.

 

So in some ways it has been a success. Will see what happens when I get my bits to put the head back on next week.

 

Tim.