Weird but beautiful: Stopped smoking

Slimlavud · #1 02-09-2010, 01:44 AM

Hi all
I have been trying to stop smoking for years - it goes in fits and starts but never for long enough...
I bought a 740 Volvo 2.4TD wagon (estate) a couple of months ago, very cheap and with what looked like a new engine fitted - very clean and not just been steam-cleaned on top. It was very rough and smoky on start-up. starting on two or three cylinders and then chiming in on all after 10 seconds or so. I suspected glow plugs and/or low compression. I checked the valve clearances - all OK. Head bolts are all tight. I changed some glow plugs but the existing ones also all tested good. Found injection pump only held on by one bolt on the flange plus the bracket bolt at the front was tight - I fitted proper bolts all round and tried moving the pump back and forth a bit to check timing roughly - have now got a dial test kit and will check it properly soon. The smoking (grey/blue smoke) continued when warm, a big cloud after idling a bit, on every acceleration with and without turbo. It was not using much oil and was getting around 28-35 mpg. No oil in the water/water in the oil etc. Changed oil for fully synthetic, still smoking the same. About 600 miles have gone by and I noticed number 1 injector dribbling from the joint in the injector body, could be run-off pipe leaking but these are new also, and injectors look new-ish too. Then suddenly, yesterday, it stopped smoking! All I can get now is some black smoke on suddenly accelerating with no load, a bit of smoke when I use the turbo - no more than normal I think. It still starts up on 3 1/2 cylinders and runs rough for first minute, then fine but not much power when cold - I am baffled - any ideas or shall i just thanks Volvo god (Thor?) for fixing it while I slept? I guess it could be a intermittent blowing head gasket or crack in the head between two cylinders closing up sometimes? Shall I just stop worrying?

Jason · #2 02-09-2010, 04:08 AM

May have had a couple stuck rings that broke loose now that you are driving it and using synthetic oil.

Jason

piper109 · #3 02-09-2010, 09:14 AM

Glad to hear your smoke has stopped. That must give you a bit of satisfaction and keep the cops off your back as you go round the North Circular.
Mine used to smoke a lot on startup and was lumpy.
I replaced the cold start device and that helped a bit. Then I advanced the injector timing to about .95 and that helped tremendously. I have to get on it quite hard now to see smoke in the rear though it does still smoke on initial startup. Much less and it is no longer lumpy and starts on all 6.
Others may see more from behind but thats OK if they dont follow too closely.
I also had an injector that would weep a bit around the body. I took it out, very carefully disassembled it in a vice and reassembled with some red loctite I happened to have, on the body threads. It has not leaked since.
Hope it stays fixed !!

Steve

Slimlavud · #4 02-09-2010, 10:07 AM

Thanks for the encouragement chaps, I should stop worrying I know. The injector I realised is just dribbling from the return hose on top... has new pipes - everything is new on the engine it seems - but needs a crimp on the clip or a shortening and new bit shoving on I think. I reckon timing it properly will help a lot too - when i have time. I wish I could find the person that 'rebuilt' this engine and find out what they actually did... If you may have seen it before, it is non-metallic red, 740 GL estate, manual sunroof, no towbar now (was one on - wires still there) and reg number G299 UAL. Was owned by someone called Mr Honey in Nottingham area and then someone else in Peterborough area...

verdigo · #5 03-07-2010, 07:19 AM

I had a similar expierience with an NA VW Rabbit. In that case it turned out to be a problem with low pump internal pressure. my 245 D24 did the same thing when I first bought it, and that turned out to be a dirty fuel filter and clogged pickup screen in the fuel tank causing low internal pump pressure. It is possible that whatever was causing the restriction washed out into the filter. If the problem comes back try putting a hose into a bucket off clean fuel, and attaching it dirrectly to the filter housing to determine if you have problems aft of the engine compartment.

v8volvo · #6 03-07-2010, 10:55 AM

Fuel restriction is often a source of odd troubles on diesels without lift pumps -- including smoking, low power, and rough starting. You can try putting a vacuum gauge in the pump inlet hose before and after the filter and seeing what kind of restriction you are looking at. Start by just changing the filter itself, as that's a cheap and easy first diagnostic step and if you haven't done it recently it probably needs it anyway.

Sounds like the synthetic oil helped your motor out, and I'll be it will really run nicely if you set the the timing to a good value. .90-.95 seems to be about ideal to me. Is your cold start advance device working?

v8volvo · #7 03-07-2010, 10:57 AM

Fuel restriction is often a source of odd troubles on diesels without lift pumps -- including smoking, low power, and rough starting. You can try putting a vacuum gauge in the pump inlet hose before and after the filter and seeing what kind of restriction you are looking at. Start by just changing the filter itself, as that's a cheap and easy first diagnostic step and if you haven't done it recently it probably needs it anyway.

Sounds like the synthetic oil helped your motor out, and I'd set the the timing to a good value for further improvement. .90-.95 seems to be about ideal in my experience. Is your cold start advance device working?