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Volvo 245 D24 NA whine from engine bay at 80-90 kmh

BigMF1155

New member
Joined
Feb 27, 2022
Only when my engine has reached full operating temperature and my speed is around 80 kmh with OD enabled, a whine begins that is high pitch and is linked directly to throttle position even if speed is the same.

This can be verified by pumping the throttle in high gear and it's very clear the whine is related to the throttle position.
I bought the car with the whine and it has only gotten worse since.

I theorize it's the injection pump because what else is linked to throttle on an old diesel? Also I have made sure all belts are tight and changed all oils for the car.

I need to get this fixed because it's driving me insane on my everyday trip to work. So the main question is what the heck could this be with the throttle position and how do I fix it??
 
The belt for the cam could be singing if it's too tight. THe big one on the front, not that little belt that drives the injection pump on the back

The belt was changed by previous owner. If it only changes from throttle and not rpm, can it really be a belt?
 
Welp I have the uncanny ability to be able to drive it and tell you exactly where what is making the sound. I've even had multiple 240 diesels in the past, even all the special tools to work on them. Done a bunch of head gasket jobs on them. ARP head studs even. My old 84 245 diesel with m46 the rear end gears whined. Maybe it that. But you say it the throttle determines the sound but only when warm and only in 5th od driving at 40mph? So replace the injection pump them if you think it's that...

Simon
 
Welp I have the uncanny ability to be able to drive it and tell you exactly where what is making the sound. I've even had multiple 240 diesels in the past, even all the special tools to work on them. Done a bunch of head gasket jobs on them. ARP head studs even. My old 84 245 diesel with m46 the rear end gears whined. Maybe it that. But you say it the throttle determines the sound but only when warm and only in 5th od driving at 40mph? So replace the injection pump them if you think it's that...

Simon


Thank you for your answer. It's probably about the rpm more than the gear I am in. Not too keen on changing the pump tho. There has to be some other way to fix this.

The weird thing is that why does it have to be warm. Regardless of the outside temperature, the coolant temp desides the whine
 
If it is related only to engine load and not RPM then I think you must be right that it has to be something involving the fuel system.

It could be the injection pump itself but I have never heard one make the noise you describe. Some other weird ideas to check just in case, these are a little off the wall but worth a look before you tear into an expensive and time consuming IP repair job:

- exhaust system: is there a place where a pipe is crimped or kinked and could be causing a howl or whistle? Remember that when you increase load, it increases the exhaust temperature and volume (due to lower density) so the system has to flow more. In a turbo engine this means the turbo spools up; in a NA engine like yours it would mean that any restriction point could become a location where noises could occur. Or, if it had a really bad restriction, it could try to find a place to leak which can make some funny shrieking sounds. Although with that much restriction it would probably have no power either so unlikely. Anyway, give the system a good inspection, look for damage and leaks.

- throttle cable: is it interfering with something or have a bad bushing where it meets the IP, so that when the engine is warm and the bushing's rubber is soft, the increased tension as you put your foot down allows the hard parts to make contact and transmits vibration into the firewall where you can hear it? I had something like this once on my 740 TD where the cable was rubbing on the brake booster and it made some scary bad noises until I found it.

- fuel system: no air in the fuel line from filter head to IP? Fuel filter is recent and in good condition?

- does it sound like the howl is coming from the engine itself, the transmission, the driveline, somewhere in the interior?

- it sounds like it is a pretty loud noise if you are being bothered by it on your commute. Is it loud enough that you could take a video and post it so that we can hear what you are hearing?
 
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