White smoke on throttle lift off...

[garym999]

This is my first bus/VW and had it just over a year. Whilst it looks the part, mechanically its not been well loved. The engine is a 1600 Dual Port pretty stock but not sure of engine history. I think it is a rebuilt jobbie though. I have gradually been getting it back to stock, gone is the cheap carb, 009 dizzy and pancake air filter. Each time it has been running and driving better till now

Any pointers as to what I might be looking for, fix wise?

The kind suggestions I have had so far is just don't lift off

It only started happening yesterday & had a show to go to today so not really had any chance to investigate. I did check the valve gaps and nothing stood out.

Overall the motor might be a little down on power but not hugely noticable. Drives at all speeds well but lift off and white smoke appears. The amount can be managed by getting back on the gas and then it stops.

The motor has also been stumbling intermittanly prior to this but does tie up with any work done. Not really sure how to describe it. If it were missing I would have thought it more regular and impactful. It's almost as though I was lifting off the throttle briefly.

I had been wondering if this was carb or ignition related. I have changed the carb out for another rebuilt Solex 34 Pict 3 and it was the same. I was thinking about checking the dizzy next but then the smoke appeared.

I'm not a mechanic but happy to spin a spanner. If it were rings I'm guessing black smoke so that only leaves the valves?
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1975 South African Fleetline

[busdaddy]

Usually that indicates worn valve guides, or piston rings. But look at the simple stuff first, like has the carb been filling the crankcase with fuel and the oil level is crazy high?, or does your bus have some silly aftermarket breather or oil filler on it?
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[garym999]

Cheers.

Oil level is spot on and certaily previousy has used very little between services. That said it is wet underneath but always has been. It also does not smell of fuel.

It did have a pancake filter and repo carb. The repo carb we replaced with a rebuilt (by others) Solex 34 PICT 3 last year. I have since managed to get another and rebuilt it myself as a spare to carry. It performs and behaves the same.

The pancake filter went by the wayside aboout a month or two ago in favour of the proper oil bath filter with the breather hose connected to that.

It's not been a gradaul thing it started just yesterday. We've driven probably another 150miles since then and so far its not got any worse, although I've probably learnt to manage it better.
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1975 South African Fleetline

[garym999]

Cylinders 1-2 are dry as they always have been.

3 & 4 wet as they have always been

When the engine was next out the push rod tubes were down to be replaced but look carefully and cyl 3 which is wet. Looks like the head might need tightening down.
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1975 South African Fleetline

[busdaddy]

I see a brake booster vacuum hose, is the inside of that line wet?, brake fluid going down?

The breather and air cleaner look great, any chance the filter is overfilled?, or accumulating oil from the breather and sucking it up suddenly when vacuum or inertia change?

Nice looking engine compartment!
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[garym999]

Again thanks for the hints.

I like to try and keep things clean although that can’t be said for the underside of the bus. You can at least keep an eye on things a little better.

Brake’s are fine and vacuum hose dry, good spot.

Oil bath filters are new to me but it’s filled up with oil to just below the line. Was on it but I’m guessing it’s wicked up in the fibres a bit. Following your thought process I wiped my finger around the inside of the air pipe on top of the carb and it’s nice and dry.

Need to get gaskets and push rod tubes ready for an engine pull I guess
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1975 South African Fleetline

[ted698]

Just for a test - I would disconnect the brake booster hose and plug the inlet manifold tap - drive it round the block - just to rule it out.

White smoke is unusual - its normally excess fuel, or something odd like brake fluid.

Have you checked for coolant loss/possible head gasket

[garym999]

Took the bus around the block today with the pancake filter refitted just for testing, Once warmed up back was the white smoke.

Took out all the plugs, disconnected the coil and fuel shut off solenoid. Wired the choke and throttle wide open and ran a compression test. First figure is dry second with 5ml of oil added to the cylinder.

1: 140/160
2: 130/150
3: 130/150
4: 120/140

The plugs were a little loose while removing them. I'm always nervous of stripping threads with plugs and these have never felt that good. Came out easy but when reinserting a little stiff.

Last time around I just replaced the plugs like for like but since I have found the Fleetline owners manual and that recommends Champion L87Y's

Being my first bus and not driven others I have been very happy with the general driving performance and top speed and not notice anything dramatic since the smoke.

I dont have the kit for a leak down test but could purchase it, would it be worth it or should I go straight a head and pull the engine.

Would I be right in thinking I should be changing the rings if so whats the run in proceedure after that?
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1975 South African Fleetline

[busdaddy]

How old are those plugs?, it doesn't look like it's burning alot of oil, unless they are just a few weeks old.
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[garym999]

They are probably about 4 months old. The bus gets out most weekends. Had it a year now and it never seems to use much oil between services.

The white smoke is as of last Saturday so not sure how much is being used now. It can be managed to a certain extent by the way it’s driven.

What’s the thoughts on the pressures. They seem uneven and all come up with a dash of oil.
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1975 South African Fleetline

[busdaddy]

4 months of weekends eh, not chronic, but making some deposits, it may go away on it's own with more use including some hard accelerating and long throttle off decels. Less old lady action and more fast and furious (without the crashes).
That compression test doesn't look all that bad either, not brand new, but not crazy bad, I've seen worse run great for years.

If the bus has been sitting alot it may be developing stuck rings, there's a way to loosen them up by drowning it with ATF, letting it sit a day and then driving the crap out of it, but the clouds of smoke it makes till the ATF burns off will get you arrested if you don't live in a rural area.

The more "environmentally friendly" method would be to slap a fresh set of rings in it, it's a weekend (or less) job and can be DIY'd with basic tools, the Muir idiot book is actually very useful for a noob doing that job.

Of course if you look hard enough while it's apart you'll find all sorts of other "I should do that while it's apart" things, you have to decide if you want to go down the "project creep" road, or put the blinders on and resolve a single issue on an otherwise good engine.

Or just stop looking in the mirror and drive on!
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[garym999]

Yes the Muir idiot book has been a godsend.

Kinda do live in rural area but cloulds of smoke would definately be frowned upon (differnent population densities).

I guess the driving style could be termed old lady but I do like to be sympathetic to engine.

I have been thinking of pulling the engine but as you say it will always add to the list of things to do. Like the weeping pushrod tubes although I have those now together with a gasket set. And I would be happy to tackle new rings.

Is there a run in period for them?
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1975 South African Fleetline

[busdaddy]

[garym999]

So given there was oil around 3 & 4s push rod tubes and number 4 jug I decided to check the head bolts on that side. They were very lose, done up but not tight so torqued them down. Could not get to the top ones.

Took it for another run. No difference the smoke does not appear immediately on lift off but as the revs drop.

I guess it’s going to be an engine pull but I don’t have the replacement push rod tubes yet. I guess for the cost it might be worth getting a set of rings.

I thought I’d check the compression again but no difference
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1975 South African Fleetline

[garym999]

Driving out and about this weekend manageing the smoke and I had a thought could it be a blown stem seal?

Once I lift of there in no fuel to the cylinders, the oil gets into the chamber and then just smokes because its not been burnt?

Do seals just go or would it indicate something else?
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1975 South African Fleetline

[busdaddy]

ACVW's don't have stem seals, a close fitting guide and the angle they are on usually prevents induction of oil, unless the guides are severely worn.
Backing off the throttle takes away combustion pressure so there's little to push any oil getting past the rings or guides back into the engine. (It's a little more complex than that, but that's the simplified version)
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[skills@eurocarsplus]

these don't have valve seals in the normal sense, and are basically run without them.

VW at some point did have an o-ring type seal on the intakes which nobody ever runs these days

when you lift off the throttle, engine vacuum is at it's highest. you are still pulling fuel through the carburetor and for sure sucking oil thru the valve guides.

if you really wanted to check for guide wear you could pull the rockers, use an on the car valve spring compressor and wiggle the valves around. honestly, probably much easier to do a top end overhaul to be honest
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[garym999]

Ok learnt a bit more Do need to pull the engine but the parts (tubes) have not arrived yet.

Just curious how it could happen suddenly? Driving around most of last Saturday then coming home it started.
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1975 South African Fleetline

[busdaddy]

Have you tried disconnecting that brake vacuum line yet?, cap the port on the manifold or it won't run, and the brakes will take more effort to stop so be prepared.
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[garym999]

No other than to check for brake fluid. Haven’t run without.
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1975 South African Fleetline