white smoke

psaboic1965 · Post by **psaboic1965** » 05 Oct 2025, 10:58

Hi all,

Grandson's 1990 240 DL sedan with 201K on it has stated to have white smoke come out of the tailpipe after starting. It diminishes a bit while driving, but never really goes away. It doesn't seem to be using coolant, and there is no bubbling in the coolant reservoir when it is running. The exhaust smells more like it is running rich than the sweet smell of burning coolant. Last compression check a few months ago was 180-190 across the board.

I'm going to be teaching him/working with him to try and fix it, but need some pointers on where to start. I'm familiar with working on 850's, S70's, and XC70's but not the common items on a 240.

Post by **BlackBart** » 05 Oct 2025, 14:22

So nice you can do that together.

It’s not blue-ish smoke?

Post by **volvolugnut** » 05 Oct 2025, 14:43

There is nothing exotic about 240 Volvos. They just keep going.
Do another compression test and see if you have a low cylinder or two.
Maybe borrow a leak tester from a parts store.
A new head gasket would not be very hard to do if needed. White smoke generally indicates coolant leak into cylinders.
If you can borrow or have a borescope, look in cylinders for very clean appearance from steam cleaning. A very clean plug would also be an indication.
vovlolugnut

psaboic1965 · Post by **psaboic1965** » 05 Oct 2025, 18:19

Nope, definitely white smoke. It's going to be a bit before we can work on it.....he has football and will drive his mom's car. I'll post more when I dig into it.

Post by **scot850** » 05 Oct 2025, 19:54

Does he do a lot of short runs? 240's were bad for condensation building up in the exhaust system, especially when doing a lot of short runs. The short runs don't allow the moisture in the muffler system to get hot enough to dry it off. If you are getting no coolant loss, take the car for a good run and see if it improves.

Also check your brake fluid level, if the seals in the master cylinder start to fail, it can leak fluid under vacuum back into the engine and burn white.

Neil.

psaboic1965 · Post by **psaboic1965** » 05 Oct 2025, 21:11

Good idea, I'll take it for a good run when I get a chance to.

122sPhil · Post by **122sPhil** » 21 Oct 2025, 17:19

im failry certain what you ave is a fuel injector that is stuck open.
whe he parks, the fuel rail slowly empties into one of the cylinders.
when he starts up it runs on 3 cylinders producing white smke for about 3 blocks then it clears the cylinder and runs ok as it is injecting.

you can connect a fuel pressure guage the rail should hold pressure, Im certain his will not hold pressure.

if you want o do this outside, go get some fire extungiuishers put them at your feet Im serious. do not do this in the shop near the house and it will never be found in a manual becuse of the obvious dangers. but anyway ignoring the danger..

pull the fuel rail out, but order new fuel injector seals because you wont want to use the old ones ever again.

order the pintles and washers dor the injectors they are cheap and one injector.

after you pull the fuel rail 10mm bolts and ull the fuel rail reconnect thoise grounds.

put a cloth under each injector.

hop in and give it a crank with a helper at the ready with the fire extingiuiser.. you do not want a gasoline fire, injecotrs atomize gas so you could also create a fuel explosion not just a fire, that is why the procedure wont be recommended by any manual.

if you start a fire or blow up your basement do not blame me..

the injectors will fire, thye will spray fuel you will see a patch of fuel on each rag all with a little evidence of the gasiline spray.

only crank for 3-5 seconds.

go look one of the injectors will be spraying fuel it isnt; sutting off,

I backflush and test them you may be ableo to backflush it , I do so my makig a reservoir with a tap I can pressurize and then release, when i pressurize the injector I use a 9V to fire it. it wont open without the power to the connector.

there is a screen in them you can buy the screens and there is a tool to remove the little basket. I found that when I backflushed it proved I had no plugging of the screen.

if you like tyou can just buy reconditioned injectors.

feeling rich? replace all 4 and you do not need to go spraying gas around and risking an explosion. just replace all 4 instead.

I found the issue myslef by dong the above and I will stress again this is not a recommended procedure due to the danger, it was obvious when I did that. hti sis my reson for explaining it in such a way.

im 99 percent sure this is your issue.

i fyou are not rich you may try just backflushign but order the pintles theere are some little washers and order the O rings, eachinjector has 2 of them get some spares they are cheap.

to get the injectors intot he fuel rail , this can be a struggle so here is my trick..

tie a boot lace so you have a hole about an inch diameter.
pu tthat hole over the injector so it holds on tot he bulbous shape.

tie a couple more boot laces around the fuel rail.

stick a screwdriver in the boot lace, keep the injector plumb to the cup on the fuel rail where it fits, if ou let it get cocked the o ring will tuck under and it wont seal and it will leak.

put oil or grease on the o ring,

stick a screwdriver through the boot lace and twist it this will put lots of force upon it and as you do watch that it is staying plumb. this will pull the injector into the fuel rail and seat it , when all 4 are installed inthe fuel rail carefully push them all at once in where they belong.

I found this hard to do with only my hands so the boot lace trick helped me .

dont use the o rings over again.

there are two types of O rings some are tan some are black , eveidently the tan ones are better with the crappy alcohol infected fuel we get now, thats just what I read
I'd use the ones you get. if you order injectors they should be included. keep a spare set in case you have to pull the fuel rail again.

if you find your hands get tired , it can be a biut of a fatige thing, take your time have a break.

once all is seated and reconnected do not drive the car without first checking carefully for fuel leaks, you could get one cocked and start a fire that way too.

122sPhil · Post by **122sPhil** » 21 Oct 2025, 17:37

I bought a 30 dollar boroscope on amazon it plugs into my phome , if you stick one in or even just check the plugs and compare that will also show the bad injector, you will see a color difference.

if you check afterits run a while it may clear and become normal again,

if you check it just after it blows white smoke and before the cylinder cleared itself, then youll see a difference in plug color for sure.

you may not need to replace all 4 injectors, do so only if you wish.
replace the fuel filter? maybe? thats up to you ! Ill warn you they are hard ot unscrew ecuuse the aluminum can will likely be corroded and a bit stuck

so reserve a bit of time and be patient.. if you do the filter and it has the OEM pump Id do the pump too, its in the same area.

I accidentally broke the small line between my filter and the pump ,becuase I struggled to gett he filter to unscrew.

be careful with it it is a short thin plastic line, I would order that too if you find it available. you can replace it the L fittings are barbed fittings. it is pushed on very tight. maybe you can get that little line with the fittings.

if you can connect a fuel pressure guage you can check for the fule rail leakdown. if it leaks it is a leaky injector but can also be a ad check valve , the check valve is near the pump.

if the check valve leaks back then it may take another turn to start instand fuel pressure by retaining it, this helps it start faster. this can also cause the rail to leak down.

a "proper procedure" is to use a fuel pressure guage to check that the fuel rail pressure holds .

if you ran it on a dyno or up a hill with a guage connected then saw that a high rev high load wide open throttle, depleated fuel pressure that may mean fuel starvation bad pump bad filter etc. hard to have the fuel pressure guage coected while driviung not impossible maybe you can monitor it with a camera..
the boroscope I got has a really long wire, maybe that could work, to monitor a guage, when driving.

work safely whatever you do

We do not want a fire to be reported as a result of all this fine armchair advice..

psaboic1965 · Post by **psaboic1965** » 22 Nov 2025, 13:25

Ok, sorry it has been awile since I posted on this.....life got in the way a bit. So, we changed all the injectors and fired it up. Ran much smoother, revved great, and no smoke at all until it had been running about 3-4 minutes then the pale white/grey smoke came back. It sort of looks like the steam that comes out of a tailpipe on a cold winter day. The higher the rpm, the more smoke. I did notice some drips of dark sooty looking water coming out the tailpipe when it was at about 2500 - 3000 rpm. Still no bubbling in the coolant tank and it smells like fresh, clean antifreeze. Speaking with the grandson, he did a LOT of short 3-5 mile trips, and the car would sometimes sit a week between driving. I wonder if I just have a ton of condensation in the exhaust that needs to be burned off? Oh yeah, oil is fine too, no milkshake. What do y'all think?

Post by **scot850** » 16 Dec 2025, 14:51

Try to take the car for a good long run to get the muffler system good and hot and hopefully get any lingering condensation out of the system. The 240's we owned were really bad for this in the UK and could rot out a mild steel muffler system in a year.

Neil.