740 with white smoke and erratic running.

[Offgrid]

My recent purchase of a 1988 740 saloon seemed to be going well, that is until it started belching white smoke, and the engine became extremely erratic. I managed to limp back to its usual parking spot, and started investigating. My first thought was a blown head gasket. There is no steam coming out of the exhaust, no froth on the oil filler cap, and no bubbles in the coolant expansion tank. The engine oil looked clean as well. I then thought the coughing might be the result of it catching the 'Rona, and I had visions of having to drive around with a mask over the radiator, But I rejected that, and decided that it needed to be triple Vax'd, the trouble is that I only have a Dyson.

On a more serious note, it belched white smoke for a couple of days, and I watched a few youtube videos about it. The guy who negotiated the purchase of the 740 turned up, and I asked him to look at the smoke. Would you believe that, when I started it, there was no white smoke at all. My current thought is that it was a blocked injector, and the smoke was unburnt fuel. Do you guys think this is the probable cause? I bought an ultrasonic cleaner, and I'm considering using this to clean the injectors - do you think this is a good idea? If so, what would be the best fluid to use? Some people suggest diluted fairy liquid, and that would certainly be the easiest for me.

[Laird Scooby]

Originally Posted by Offgrid

My recent purchase of a 1988 740 saloon seemed to be going well, that is until it started belching white smoke, and the engine became extremely erratic. I managed to limp back to its usual parking spot, and started investigating. My first thought was a blown head gasket. There is no steam coming out of the exhaust, no froth on the oil filler cap, and no bubbles in the coolant expansion tank. The engine oil looked clean as well. I then thought the coughing might be the result of it catching the 'Rona, and I had visions of having to drive around with a mask over the radiator, But I rejected that, and decided that it needed to be triple Vax'd, the trouble is that I only have a Dyson.

On a more serious note, it belched white smoke for a couple of days, and I watched a few youtube videos about it. The guy who negotiated the purchase of the 740 turned up, and I asked him to look at the smoke. Would you believe that, when I started it, there was no white smoke at all. My current thought is that it was a blocked injector, and the smoke was unburnt fuel. Do you guys think this is the probable cause? I bought an ultrasonic cleaner, and I'm considering using this to clean the injectors - do you think this is a good idea? If so, what would be the best fluid to use? Some people suggest diluted fairy liquid, and that would certainly be the easiest for me.

I'm asuming it's a petrol engine because you haven't said. Have you checked the oil separator and flame trap in top of it? If those are blocked, it's possible it's pulling in engine oil via the inlet manifold and burning that - burning oil gives white smoke. Unburned fuel will give black smoke and a mixture of oil and petrol (usual sign of leaky valve guide seals) is blue smoke.

You also failed to mention whether it was a turbo or not but being a 740, unlikely (although possible) but if it is a turbo, the turbo seals and/or bearings are probably shot.

Adding the engine code (usually on a label on the upper timing belt cover) will be helpful here in directing you to the exact cause of the problem.

[Offgrid]

Sorry it's a normally aspirated 2 litre injected redblock engine. I did have another problem, and I seem to have fixed that by replacing the fuel pump relay. Could that have some relevance to the white smoke?

[Laird Scooby]

Originally Posted by Offgrid

Sorry it's a normally aspirated 2 litre injected redblock engine. I did have another problem, and I seem to have fixed that by replacing the fuel pump relay. Could that have some relevance to the white smoke?

None at all - is it K-Jet or LH2.x injection?

[360beast]

Originally Posted by Laird Scooby

None at all - is it K-Jet or LH2.x injection?

1988 will be K-jet

[Laird Scooby]

Originally Posted by 360beast

1988 will be K-jet

I missed the 1988 because i was looking for the other info Luke. You're right, it will be one of the first B200E K-Jets.