with 55,000 original miles blows white smoke on acceleration. What are safe additives to reduce that?

 

engine might need the head gasket replaced or the heater tap might be injecting coolant into the engine.

 

There are several possible causes of what you are seeing. I don't expect any can be resolved via the engine oil. Is the smoke really white and are you sure the it is on acceleration and not on lift off afterwards? If the latter, it's likely to be oil going past the valves, almost normal with our engines and not anything to worry too much about.

 

Check your brake fluid level as well, white smoke can also be caused by the engine sucking in brake fluid from a worn remote servo.

 

Really white smoke, as opposed to light blue to grey, from the exhaust of a well warmed up engine is likely to be a failed head gasket. As it's not a small job to change, you want to be sure of the diagnosis. Once you are sure, don't use the car as it will increase the damage. Without overheating or severe neglect, I'd be surprised that a 2.4, 3..4 or 3.8 blew a gasket at only 55k miles.

 

These cars have a Reservac tank that has vacuum and allows the servo to operate if the engine stops and there is no vacuum in the inlet manifold. To do this, there is a pipe connecting this tank with the inlet manifold. If the brake servo has a fluid leak, this can enter the servo piston chamber and can then get sucked into the inlet manifold via this pipe. Hence the white smoke. You can test for this by blocking or clamping the pipe to the inlet manifold, then rev the engine up to see if you still get white smoke. Be careful if you road test, as clamping the servo pipe means you won't have any brake assistance.

 

Check your fluid levels.

If you are down on brake fluid then yes it might be brake fluid being burnt off but you will notice the drop in fluid level.

If you are continually having to top up your radiator with water then you might have a head gasket problem but very rare. You can check for a head gasket failure by having a compression test done on the cooling system. A local garage should be able to assist with this. Basically they put a pump onto the radiator cap and pressurise the system. The pressure will either remain constant, water will be peeing out of any hose or joint with a leak or there will be no sign of a water leak but your pressure gauge will drop. Also check the oil colour. If it is turning milky or it has some creamy foam forming on the inside of your cam cover it is a head gasket.

 

Buy a cheap test kit from Halfords, AutoZone or whoever that will tell you if there are combustion by-products in the cooling system. Soon tell you of you have a head gasket leak, crack in block, corroded head, etc.

Does it blow white smoke continuously on acceleration or only a puff & then clear?

Does it blow white smoke fully warmed up?

Don't put any additives in the oil. All you do is take it out of spec. The only time that possibly warrants putting additives in engine oil is when the engine is badly worn and all you are doing is delaying the inevitable rebuild.

If the smoke is tinged with blue make sure engine breather screen is not clogged.

 

If you do Fraser's check, the vacuum line joins the top of the inlet manifold near the rearmost cam cover nut. It's a metal tube that goes through a few right-angles to dip under the carbs where it swaps to rubber. It runs along the side of the block, then down past the brake booster to the T and non-retrurn attached to the vacuum reservoir. That's just above the horizontal diagonal brace to the front cross-member.

I'd be very reluctant to drive the car without the brake booster working, especially if the car's not been used much and the wheel cylinders may be sticking.

 

why not just disconnect the booster vacuum hose from the intake manifold, warm up the engine in place, then accelerate the engine ? If the white smoke persists after a while, it's a head gasket or even a heater valve.

The MK-2 has a "normally OPEN" HEATER TAP unlike the S type which has it "normally CLOSED".

BUT there is no set mileage for a head gasket failure, if there was an overheating episode at any earlier mileage, it can cause the cylinder head gasket to fail, and the result is also white smoke.

I had a similar situation in my 3.8 engine and it happened every time I turned the Heater ON. Replacing the heater valve resolved the white smoke during accceleration.

 

The Mk2 has no heater connection to the vacuum system, the tap is cable operated. So heater valve is out for Mk2 & their derivatives,

 

That makes no sense, while I don't doubt that what ever you did solved you white smoke issue, replacing the heater valve should not have done anything.
Unless it was leaking all over the exhaust manifold, I can see that.

 

Jeff. On an S Type the heater valve (28) is vacuum operated & if the Diaphragm ruptures or the metal centre corrodes through ~ (more common) you suck coolant direct into the vacuum system & thus through the engine. Mk2 not so with cable operated valve..

 

This may well be one of the first of the modern car phenomena, where nominally unrelated systems start to interact in unexpected ways. A world where electric windows become slow because of something in the ignition system.

 

the original valves have a weep hole through which they leak when the diaphragm tears inside, but not enough to cause white clouds of smoke burning coolant over the down pipes.

the clouds of smoke were indeed caused by the heater valve injecting coolant in the intake manifold and burning it in the combustion. I took the car to the mechanic and the first thing he asked was Did you have the Heater on when this happens? I said yes and he said it is the heater valve, replace it..

I found a replacement valve and the white clouds of smoke stopped.

If the MK-2 does not work like the S type, then it must be the cylinder head gasket or the brake servo leaking into the poster's engine.

 

Yes, I understand now Jose, thanks.

And after seeing those photos, I remember them from another thread Glyn.

 

If in the past they ran water as cooling fluid, then it could even be the waterways of the head corroded away.
This has happened on my S-type 3.8 , blowing white smoke.
Had to replace the head in the end.

 

Thank you all for the feedback. It seems driving the 340 is mostly the "cure". The prior owner drove less than 100 miles in the two years he had it and now that I've had the oil changed as well as a "wellness" update - clutch, brakes, signals, horn, ALL fluids, hoses and belts it "smokes" less by the day. Again, many thanks, I look forward to adding comments when I've had a chance to enjoy the car more.

 

Assuming all else has been checked as above.
When the neighbor gets a new to him jalopy, he runs a vacuum source inside the car. As he accelerates hard he lets the car have a little drink of ATF. White smoke ensues. When the smoke subsides, he accelerates and gives the ride another drink. Repeats until a quart of ATF is gone. Lubes the top end, removes soft carbon from the valves and pistons. End result is a better running engine with more power.

 

Thank you