N/A D24 loses power nearing max revs, brown black grey smoke

[jpliddy]

Originally Posted by 245d6

so i have this 245 d6, 300.000 km's, 1983, which runs quite well (i suppose, only used to air-cooled gasoline engines so i try not to worry to much about some ticking, valve noises etc.). It starts okay, seems like it has one bad glow plug. It starts immediately but makes a bit of a noise for the first 10 seconds and smokes a bit for about 30 seconds. But this isn't my biggest concern, something quite simple to fix it seems.

The biggest issue is that it won't go over 110 km/h, especially when giving it full throttle it eventually goes slower, starts to smoke brown/grey/black. If i let go of the gas it gets better and eventually i can get it a bit above 110 on the counter. Up until 100 no issues at all.

Some background:

Car had been sitting since 1999 (from the papers i got, never spoke the old owner). No idea about maintenance, but when i got it it was hard starting, lots of white smoke for the first 2 minutes.

Changed the timing belt and ip belt ''according to procedures'': Built my own tools for the pulleys and found a cheap euro vw diesel tool set that contained the little tool for the camshaft position, dial indicator & locking pin for the ip gear. One difference with the ''real'' volvo tools: Putting a .2mm feeler guage between surface didn't really do anything, still bit of play on the locking tool. However it became much better, easier to start, less smoke and less noise. I don't remember exactly what i set the pump to, but i think .85mm.

After welding the car back together, redoing the suspension and brakes i finally managed to get it through the technical check in order to get it road legal again and was able to really drive it for the first time.

Some things i noticed:

Fuel pump seems to make a bit of a zooming? Noise when idling, goes away when i touch the throttle a tiny bit (don't know if this is problematic, maybe belt is a bit too tight?) sounds like a bearing with a tight belt, but i thought i read that the pump doesn't have any roller bearings.

Spews quite a bit of vapour / oil from the crankcase breather, so much that the entire intake is full of black ''grease''. This was already when i got the car, and i still need to remove the intake and clean everything. Planning on rerouting the crankcase breather into a catch can. In the first 500km's the dipstick went from full to reading 3/4, when i take of the breather tube i think i know where the oil is going... I don't really mind at the moment, maybe pull the engine out next year and rebuild it but for now i would like to just drive it for a bit.

Injector at the rear of the engine is a bit sweaty, was leaking last week but magically solved itself, now the 3rd injector has started leaking. Not too bad, no diesel under the car but they're wet. Is on my list to fix.

No clue if the cold start device is working, it was disconnected when i got. I suppose it is in ''warm'' mode but have no clue on how to check, could be a reason for my issues maybe.. Car always starts, even with bad battery and -10 celcius weather (despite some smoke at those temperatures)

when replacing the brake lines i noticed the fuels lines under the car are quite corroded, didn't replace yet but maybe this is part of the problem i'm having.

Bit of a ticking noise sometimes, sounds like valves which i still need to adjust, is on my list and i don't think it has anything to do with my problems. Old engines make a bit more noise (what i've learned)

here is a youtube link to a short video of the issue:

https://www.youtube.com/shorts/wcdeubljoyk

too bad my friend decided to film me rather than the disgusting stuff coming out of the exhaust of my car but i think you can make out the noise it starts to make as it revs up and see at least some of the smoke coming out of my leaking exhaust. I didn't want to unnecessarily rev it to redline again.

So the problem is not a ''power'' problem i suppose, it does the same thing in neutral when revved to max, same thing in 1st, same in 2nd (pulls to 60 km/h, then slows down to 50 km/h as it starts to smoke), 3rd and eventually 4th (it's 4-speed with od but od isn't working yet, problem for later).

Trying to come up with a plan at the moment:

1. Replace fuel line from hard line to pump with a clear line to see if there is air in the system. I'm not sure if this is the issue as it smokes black / brown / blue but figured i might check as it's easy.

2. Clean air intake, reroute crankcase vent tube into catch can. My theory: As car starts to rev up, more pressure builds up, more oil gets thrown out in to the intake system which is then introduced into the combustion chambers, making the engine run ''rich'' on diesel / oil / air mixture?

So far no runaway situation so can't be too much, but maybe this could be the problem?

3. Recheck pump timing, maybe i screwed up somewhere and it's off, resulting in too much fuel at max revs? Don't know if this could lead to the engine bogging down and losing some power.

To be honest, i don't mind not driving over 100 km/h / 60mph, but would prefer the engine to be as ''healthy'' as possible, considering its age and me having no idea about how it has ever been maintained. Also no idea about d24's, maybe 100km/h is it's top speed with only 4 gears? It is slow..

hi 110 klm is quite slow i have never really pushed my car to its limit it will do 85mph but may do more hopefully you can get the car sorted out with the help of these guys here if they cant fix it no one can .

[245d6]

Update:

Finally got the engine ''running right''. Now it makes it to 130 km/h in 4th gear, no overdrive. But several new problems came up, most importantly it overheated / boiled it's water (managed to shut engine off immediately only I noticed the temp gauge and steam from the front.) when driving on the highway at full speed / load.

This is what I replaced / noticed before overheating:

Redid the whole cooling system with new radiator hoses (aftermarket available in Europe), silicone parts & copper tubing for the smaller hoses, most of them were leaky / wet. Also flushed coolant system, radiator & put a new thermostat in (87 degrees). Noticed there was a lot of corrosion in the system, not only brown deposits in the hoses but actual flakes of rust coming off all surfaces when I took out the thermostat and other hoses going to the engine. Tried to get everything out with magnet on a stick but I suspect the whole engine is full of it. Might be a cause for the engine to run a bit hot?

Adjusted the valves, most of them were too tight (one didn't even have any play). Also changed the fuel filter for a new one & replaced injector return hoses. I suspect the valves being too tight was the cause for low power at high revs.

After this I went to Germany for a day so took the volvo to do a bit of italian tuneup on the autobahn. First ride was going well, went a bit easy on the car to check if nothing fell apart. Noticed the engine was running 3/4ths of the temp. gauge most of the time and when going full throttle even past it. Kept speeds down but mostly stayed at 3/4ths, sometimes half when going downhill. It burned quite some oil, 1 liter in 500 km's

On the way back I wanted to check out the top speed because it stopped smoking a lot at 110 km/h and went faster than that. Drove the car until gps said 130 while keeping an eye on the temp gauge. Went up a bit but stayed there mostly, checked my mirrors and saw mostly black smoke behind me, checked temp gauge and it was in the red zone and engine started to make a loud ticking noise. Immediatly put engine off, coasted to the side of the highway and let it cool down. It threw out quite some water through the cap but only when I was stopped. No water trail behind the car.

After refilling it (i took 10 liters of water with me just in case), starting it up and waiting a bit I drove it to the nearest parking lot to investigate.

Engine seemed fine, oil wasn't at top mark so refilled again. When starting, glow plug light didn't come on and it needed quite some cranking over to get started. Drove the car home without further problems, no overheating and no loss of coolant. Still, temp meter was a 3/4th.

Do have to admit that for the full journey I filled the car with demineralised water to check for leaks and to try and clean out the rust. Maybe part of the issue? Does coolant cool more than water?

Next day, hard to start the car, needs quite a lot of cranking when cold and smokes more on startup. Pretty loud knocking / ticking noise from somewhere in the engine, sounds like it's coming from the bottom end bearings. But the noise got a lot less after then engine warmed up a bit, still runs the same for the rest. Checked the hoses with a laser, when gauge is in the middle it's +- 90 degrees. When engine is fully hot noise is almost gone / unhearable because of other noise.

Today I checked again, cold starting the car with the noise and then loosening the injector pipes. Sounds like it goes away with injector 6. Could I have cooked an injector by overheating the engine? This is the same one that has been a bit leaky / sweaty since the beginning.

But on the good side, found a second engine nearby, 105k miles and the guy says it was running good. Let's see if its something, maybe fix one while the other is in the car. First going to do some alternative fuel experiments with this one.

[ngoma]

Originally Posted by 245d6

actual flakes of rust coming off all surfaces when I took out the thermostat and other hoses going to the engine. Tried to get everything out with magnet on a stick but I suspect the whole engine is full of it. Might be a cause for the engine to run a bit hot?

Especially if the radiator small passages are clogged with it.

Originally Posted by 245d6

Noticed the engine was running 3/4ths of the temp. gauge most of the time and when going full throttle even past it. Kept speeds down but mostly stayed at 3/4ths, sometimes half when going downhill. It burned quite some oil, 1 liter in 500 km's

Not good to run the engine hot like that. Excessive overheat can also permanently relax piston ring tensions (including oil control rings).

Originally Posted by 245d6

On the way back I wanted to check out the top speed because it stopped smoking a lot at 110 km/h and went faster than that. Drove the car until gps said 130 while keeping an eye on the temp gauge. Went up a bit but stayed there mostly, checked my mirrors and saw mostly black smoke behind me, checked temp gauge and it was in the red zone and engine started to make a loud ticking noise. Immediatly put engine off, coasted to the side of the highway and let it cool down. It threw out quite some water through the cap but only when I was stopped. No water trail behind the car.

Usually better not to turn off engine while overheating. Let it run at idle slightly faster until temps come down. Shutting it off when overheated tends to concentrate the heat as there is no longer any coolant circulation.

Originally Posted by 245d6

Engine seemed fine, oil wasn't at top mark so refilled again. When starting, glow plug light didn't come on and it needed quite some cranking over to get started. Drove the car home without further problems, no overheating and no loss of coolant. Still, temp meter was a 3/4th.

3/4 on the temp. gauge is overheating!
GP system has a temperature sensor circuit that limits GP energize when the engine is hot (as GP help shouldn't be needed).
Hard starting while hot (no GP) often indicates poor compression.

Originally Posted by 245d6

Does coolant cool more than water?

No. Water has higher heat transfer capability.

Originally Posted by 245d6

Could I have cooked an injector by overheating the engine? This is the same one that has been a bit leaky / sweaty since the beginning.

Cooked injector more likely from a faulty injector heat shield. General engine overheating usually first attacks the headgasket, warps the cylinder head, melts pistons, scores cylinder walls, weakens piston rings, damages bearings.

[245d6]

Oh well, lets swap engine and take this one apart to find out. It did sit for 20 years with only tap water in it so coolant system is probably full with rust.

I have a (new) d24t radiator. Didnt fit with current hoses but will switch them with other engine. Also my mechanical fan has no cowl or air box, would that matter? And thermostat its a 87 degrees one, is that okay.

I notice it heats up REALLY fast under load. Going uphill slowly, it can go from cold to 1/2 temp gauge in a minute or so..

Still strange, i measured temperatures again today, 3/4 of the gauge was 100 degrees, not that hot right? My motorcycle goes up to 120 on hot days without problems, but that is air cooled..

[ngoma]

Originally Posted by 245d6

I have a (new) d24t radiator. Didnt fit with current hoses but will switch them with other engine. Also my mechanical fan has no cowl or air box, would that matter? And thermostat its a 87 degrees one, is that okay.

What radiator is in there now? Maybe that's what is causing the overheat problem-- wrong radiator (too small) in addition to being clogged with rust flakes?

Fan shroud most helpful at lower road speeds as it improves the fan's efficiency.

Originally Posted by 245d6

Still strange, i measured temperatures again today, 3/4 of the gauge was 100 degrees, not that hot right?

How did you measure? Normal operating temp. more like 90*C.

[245d6]

2nd hand d24 240 radiator. I flushed it multiple times. Also bought another d24 radiator (nos) but hose connections are on different sides. Will get new hose to run the new new radiator in the future.

Measured with laser on top radiator hose / head.

Yesterday I changed the oil, no water, no debris(bearings), did smell very bad (burnt).

Listened to the whole engine with screwdriver to my ear, can't really find anything unusual, except some injectors are louder than others. Even put car on lift to listen to the oil pan, no strange bearing knocks there.

Rerouted crankcase breather into a can, now know where all the oil is going. Quite some oil in the can after 40km drive.

Today further investigation into the ticking noise and another coolant flush. Did notice temperature was better yesterday, gauge in the middle all the way to 120km/h

Also, noticed left rear brake drags a bit (wheel was warm), extra resistance, engine needs to work harder? Or maybe it got hot because of constant overfueling through crankcase breather?

[ngoma]

Originally Posted by 245d6

2nd hand d24 240 radiator. I flushed it multiple times.

If the passageways are clogged it can be difficult to impossible to clear it by simple flushing. Radiator shops remove the end tanks and use metal rods to physically "rod" out the small passageways.

Why not test the radiator with your laser thermometer? Take readings from different locations on the radiator. Should be near uniform gradiated temp. difference as you work from the inlet to the outlet. Distinct cold spots indicate clogs.

Originally Posted by 245d6

Also bought another d24 radiator (nos) but hose connections are on different sides.

Guessing one of them may be for a different model (7xx?).

Originally Posted by 245d6

Also, noticed left rear brake drags a bit (wheel was warm), extra resistance, engine needs to work harder?

Obviously, but unless it was really locked probably not causing engine overheating by itself. The brake would be smoking and red-hot.

Originally Posted by 245d6

Or maybe it got hot because of constant overfueling through crankcase breather?

Not likely.