26 replies to this topic

[Midas Mk1]

Hi all,

 

Following on from previous issues of stalling when under load, i've reset the dizzy timing to be 31 deg at 4k, as per they r/r setup I had.

 

The idle is alot smoother (for a 276), and revs smoother too, however on idle, and throttle, white / blue smoke is pouring out the exhaust.

 

It's recently had new valve stem seals (MPi type), new HG etc, and i'm thinking the valve guides could be at fault?

 

Done a compression test, with 15bar across all of the cylinders, all the same pressure.

 

 

When on the dyno, I only saw it puff some smoke when >6k revs

 

 

Are there any more checks that I can do before I whip the head off? The only other thing I can think of is to make sure the servo take-off isnt sucking in brake fluid?

 

 

If it is the guides, are they any recomended machine shops in the north west? Im against a tight deadline for the car as I have a week or so to get it mot'd, being a 37/32 fully worked head with offset valves, will this effect the valve guide fitting process?

 

 

Thanks

 

Sam

 

Edited by Midas Mk1, 15 August 2016 - 11:28 AM.

[Midas Mk1]

Link for the video :

 

http://scontent.cdni...138554535_n.mp4

[Wim Fournier]

First question coming to my mind is; did you lose cooling liquid.

If you see white smoke there is water coming in the cilinder(s) you should think.

If this occurs the quantity of cooling liquid must diminish. And you should see that in the overflowing bottle of the radiator.

With all the work that you have done on the head, perhaps the waterjackets have gotten a leak somewhere?

When cooling liquid is coming into the cilinders, you should find mayonaise in the rockerbox and coolant in the engine oil.

When you change the oil in the future, better use 10W40. The friction plates in the gear box love that much better than the 'thick' 20W50.

 

What is coming out off the exhaust pipe is 'no good'!

Edited by Wim Fournier, 15 August 2016 - 11:56 AM.

[Carlos W]

Is it using brake fluid?

 

What conditions does it smoke under?

[Midas Mk1]

I've literally done 5 miles driving with it since a cam swap / hg change,  so havent noticed any drops in radiator fluid or brake fluid. Smokes a little on idle, alot when the throttles open (especially on a snap of full throttle), it's not drivable as it is is as it leaves a big cloud after each prod of the throttle. 

Going to check the brake fluid when i'm home, also to check the vacuum pipe for signs of fluid. 

 

There's no mayo in the oil, its top quality 20 50 CTV so should be perfect for it, compression is good too, and it runs ok, apart from the smoke!   

Head wise, I cant see there being a problem with the water jacket, its not been ported recently, and put out a healthy power figure on the dyno, it's why I'm thinking it could be the valve guides, but don't really want to rush getting the head off incase there's other things I can check first/. 

[Carlos W]

Give it a run. It could just be condensation or traces of contaminants 

[Wim Fournier]

Oké, next questions. Have you the positive crankcase ventilation installed in the proper way? If not, than there is no depression in the crankcase when you take your foot from the throttle pedal. When the throttle closes no air can come in via the carburetter and the pistons that go down with the inlet valve open suck the hell and make a deep vacuum. Above the inlet valve there is a bath of oil standing in the pockets where the valve stems go down in the valve guide. When you have no oil seals on the inletvalve stems, oil is entering into the burning room above the piston. Only via the crankcase ventilation there could be a proper vacuum inside the rocker box, since the pcv is building its vacuum via the pipe at the foot off the carburetter. In this way equalising the sucktion in the inlet port off the head with the sucktion under the rockerbox.

When the valve guides were installed were they reamed in the right way? If not, then the valve stems have opened up their way in their own way and the valve guides are worn out already so that a lot of oil can go down when you take your foor from the throttle pedal.

 

If not; take the car out at night and blow away and keep high speed for a while so that it gets really hot. Possibly all your smoking gets over in a while.

Edited by Wim Fournier, 15 August 2016 - 04:40 PM.

[Midas Mk1]

Update: just blocked off the servo take off, immediately less smoke on start up, but as it started to warm up thicker blue / white smoke on idle and revs, wouldn't clear after 5 mins including a run!

Took the filler cap off the rocker box and no smoke was coming out, does this suggest valve guides?

Was really hoping it was servo related!

[Midas Mk1]

The crankcase breathers are as factory on the timing case and clutch casing, fed to the carb rather than fresh air too. (Hif44)

Edited by Midas Mk1, 15 August 2016 - 05:09 PM.

[Midas Mk1]

Well, head off. Oil on the piston crowns, oily looking valve guides, looking like I need them replacing.

 

Is it do-able at home? really pushing for time with it, does anyone recommend a good place in the north west where they could be done? 

 

Think the valves are offset, will this cause any issues?

 

Thanks

 

[Carlos W]

Turbo Phil is in Kendal.

 

It's not really a DIY job

[carbon]

+1 unlikely to be a DIY job if the valves are offset. Chances are the valve guide bore will be offset. So to get the valves lining up with the seats you will need exact same amount of offset in the guide, and also fit them correctly...

 

And if the guides are offset I don't think standard valve guide oil seals would work.

[Midas Mk1]

+1 unlikely to be a DIY job if the valves are offset. Chances are the valve guide bore will be offset. So to get the valves lining up with the seats you will need exact same amount of offset in the guide, and also fit them correctly...

 

And if the guides are offset I don't think standard valve guide oil seals would work.

 

Recently fitted MPi type oil seals to them, so could doing this have caused the leak / smoke?

 

Typically these things always happen when I need the Mini on the road asap, are there special offset valve stem seals? This might be  the root cause?

[1984mini25]

Did you have seals on all 8 valves? Some say you only need 4, but tend to help if fitted to all.

[Midas Mk1]

Yep, my Dad fitted all 8 MPi type oil seals whilst changing to Swiftune road spec springs, got another head I could maybe use, but then that has a higher cc so will lower the compression ratio.

 

I didn't realise that there was different seals for the offset valves, maybe this is the reason, as the only smoke I saw previously was past 6k on the dyno, and that wasn't 'that' much.

Edited by Midas Mk1, 15 August 2016 - 10:05 PM.