240 General: Low-Pitched Whine At Slow Speeds

[TheHungriestBadger]

Hi all,

Just replaced my transmission mount (1990 240GL, B200F, AW70 trans) with the help of a mate, and now I have a new noise. As in the title, I have a low-pitched whine at slow speeds (possibly at higher speeds but it's very quickly overwhelmed by road noise). I have two analogies, take your pick:

1) It sounds like the noise modern EVs make when travelling at slow speeds.
2) It sounds almost identical to the electric window motors in pitch and 'coarseness'.

I'm hoping it's just something like the centre carrier bearing rubbing, or something along those lines, and not something more sinister. It's speed-dependent and not RPM-dependent, so far as I can tell... Radio was fully turned off as well so unlikely to be noise from ignition interference.

I'll likely be dropping it off at a local trusted garage at the earliest possible opportunity unless someone on here tells me to quit worrying and just 'send it and see'. Would be good in the meantime to have some possibles on what it could be.

Given the fact I've just replaced the trans mount, I'm guessing it's to do with the driveline at some stage? Also, by slow speeds I mean 20mph or less, above that there's too much tyre noise to discern whether it's still there. Noise is present both when coasting in gear, and when accelerating, I haven't tried coasting in neutral yet.

Finally, it's NOT the noise made when the transmission filter is clogged - my trans makes that noise only when first pulling away from cold and it's much higher-pitched than this new noise.

Cheers in advance,
Adam

[TheHungriestBadger]

For even further clarification, the noise sounds almost the same as in this video (https://www.youtube.com/watch?v=CvmZ...nnel=TomMorton), especially when the vehicle in the video is left to coast at approx 6 seconds in... I guess this could be the issue, although it'd seem strange for it to crop up only now? Again, presumably how the trans is now sitting slightly differently has affected something along the line?

If it helps pinpoint at all, the car has (and always has had) a tendency to slam into gear pretty harshly when shifting from D -> R or R -> D, but only once the ATF has warmed up and thinned a bit, when cold there's almost no noticeable thud at all. From previous reading I've done though, this could be caused by play in the driveline anywhere from the tailshaft bushing through to the diff, or any play in the rear suspension setup, so probably doesn't help much.

[Bob 1967]

.

If the gearbox is leaning/pressing on the driveshaft it will push the defect though the driveline and up to the diff, that will definitely produce a whine as described.

[TheHungriestBadger]

Hi Bob.

Your mention of whether it was new or not reminded me how the threads on the old mount (quite possibly original to the car), were not in line.

The one that came off the car looked like the attached photo. The attached photo also clearly shows that the threads are not in line, this was the case with the old one that came off of my car - is this intentional (PLEASE CLARIFY)?

The one I have put on is one of the round ones, same thickness, and the diameter matches the width of the squarer one pictured; however, the threads on the one I installed WERE bang in line with one another from all angles. Would this be enough to cause the symptoms do we think? I'd really rather not have to repeat the job, but if I have to, I have to... I probably can't cause any more damage than whatever I have done already (although, please car gods, smile on me today &#128566.*

If anyone can clarify the offset of these threads being an issue, factually, or anecdotally, I'd love to hear it, it'll be the better part of two weeks before I can tackle this again myself anyway so plenty of time to get some opinions.

* I don't think they are, I've just gone to retrieve the old mount from the boot, and had a quick peak underneath, I've got coolant leaking from the rad (presumably, it's dripping off the front cross-member) and I noticed a lot of fresh looking oil covering the front of the transmission pan, presumably engine oil since it doesn't look red, although this could've been a pre-existing problem. I must've jacked the transmission up too far when reinstalling the trans cross-member. I'm properly kicking myself right now, it was a £10 part and I've probably just cost myself hundreds (at least) by messing it up. If coolant has mixed with the ATF, call that thousands. Feeling pretty gutted to say the least... I'll have to inspect it properly tomorrow, although I'm not looking forward to it.

Alternative Links:
https://drive.google.com/file/d/1TrU...usp=share_link

[Othen]

Good morn,

Are you certain the whining noise wasn't present before you changed the gearbox mount? If so then something must have been disturbed or misaligned when you put it back together. The most likely culprit would be the prop-shaft centre bearing. It is pretty cheap and easy to change though, this may help:

https://www.volvoforums.org.uk/showp...postcount=1888

The mount you replaced had probably got a bit distorted over the last few decades, this is pretty inexact science so I wouldn't worry too much about it.

I would not have thought a coolant leak or engine oil leak was anything to do with changing the gearbox mount - one would have to move the engine a very long way indeed to rupture anything. Have a look at the transmission cooling lines that run from the right side of the gearbox to the radiator. They are hard lines and so quite a bit less flexible than the engine coolant hoses. If you have a leak there it will be very apparent.

Just be methodical now and find out where the coolant and oil leaks are coming from, my guess is they are unconnected to changing the gearbox mount, but they still need fixing. Let us know how you get on.

Abe

[Bob 1967]

This is my mounting, my gearbox is a BW55 though.
I shortened the studs on the crossmember end.

Are your engine mounts okay?
My engine mounts went around the same time as the gearbox one.
And the complete unit shifted back, only a couple of cms, but it was enough.
As Alan says, the centre bearing could also be the culprit.

[Othen]

Originally Posted by Bob 1967

This is my mounting, my gearbox is a BW55 though.
I shortened the studs on the crossmember end.

Are your engine mounts okay?
My engine mounts went around the same time as the gearbox one.
And the complete unit shifted back, only a couple of cms, but it was enough.
As Alan says, the centre bearing could also be the culprit.

That is a good point about the engine mounts Bob, if one mount has failed that will put more stress on the other two.

They are pretty easy for the OP to change, this might help:

https://www.volvoforums.org.uk/showp...postcount=1347

[TheHungriestBadger]

Okay, so damage inspection done, and I think I have actually got lucky after all. The coolant leak was [my excuse for] the blanking plug for the aircon having worked its way loose slightly. I realised shortly after seeing coolant on top of the upper ATF cooler line.

ATF cooler lines aren't obviously leaking, they are covered in something (the generic black oily substance that's leaking from somewhere), but there's no dripping coming from them directly, even with the engine running. Likewise with the dipstick tube, I even topped up 1/4L of ATF to double-check it wasn't leaking, and it's not.

So, next steps then are to order the CORRECT transmission mount, along with new engine mounts, and just get my local garage to fit them and make sure everything's back in alignment. Maybe when I retire this to second car duty (likely this time next year), I'll be more inclined to work on it myself again.

Thanks Bob and Abe for keeping my nerves in check and giving some good pointers to what could've gone wrong, I feel like something definitely has shifted, and engine mounts had already made their way onto the 'probably should do them' list.

BIG RELIEF (for now)

[Othen]

Originally Posted by TheHungriestBadger

Okay, so damage inspection done, and I think I have actually got lucky after all. The coolant leak was [my excuse for] the blanking plug for the aircon having worked its way loose slightly. I realised shortly after seeing coolant on top of the upper ATF cooler line.

ATF cooler lines aren't obviously leaking, they are covered in something (the generic black oily substance that's leaking from somewhere), but there's no dripping coming from them directly, even with the engine running. Likewise with the dipstick tube, I even topped up 1/4L of ATF to double-check it wasn't leaking, and it's not.

So, next steps then are to order the CORRECT transmission mount, along with new engine mounts, and just get my local garage to fit them and make sure everything's back in alignment. Maybe when I retire this to second car duty (likely this time next year), I'll be more inclined to work on it myself again.

Thanks Bob and Abe for keeping my nerves in check and giving some good pointers to what could've gone wrong, I feel like something definitely has shifted, and engine mounts had already made their way onto the 'probably should do them' list.

BIG RELIEF (for now)

Okay, that is good news, although I was almost sure there couldn't have been a connection between changing the transmission mount and a leak.

I'm not sure there is anything wrong with the transmission mount you have fitted, I think I fitted one like that to the RB (checkout the second link I sent you).

It is most likely that your two engine mounts need changing and you disturbed them from their resting place when you changed the third mount. These are pretty easy to change (see the link), the cost will be almost all labour if you get a garage to do it, so why not just do it yourself? It is easiest and safest with an engine hoist, but if you don't have one then a brace like I used (started off life as a rear chassis member for a Fiat Panda) is good, or you can just use a jack and some wood under the sump (do one at a time). The left hand one is easy-peasy, the right one a bit more difficult to get access due to the exhaust. You could do this on your drive in a couple of hours on Saturday morn - or a garage might charge you £125 in labour.

https://www.volvoforums.org.uk/showp...postcount=1301

I doubt very much the transmission coolant lines will be leaking; they are stainless steel and pretty strong. You mentioned a problem with the transmission in your first post. If you haven't done so already then change the ATF - it will probably fix the transmission issue you have. There is a hard (by the book but messy) way and an easy way to do it. The hard way is to divert the output line into a bucket whilst you run the motor and gearbox in gear whilst simultaneously refilling it with just enough fluid (don't try this at home kids). What I'd recommend is sucking the fluid out of the filler tube with an electric pump (cost about £15 on eBay if I recall), you will be able to remove about 3 litres of the ATF at a time (all except the stuff in the torque converter). Refill with with ATF, drive 500 miles and repeat. Do this again after another 500 miles and you will have changed about 90% of the fluid after the third partial change. You will probably find your transmission is much improved - this is something you could easily do yourself.

Good fortune .

[TheHungriestBadger]

ATF is all nice and red these days, it's had plenty of drain-refill cycles at this point. Regarding why I don't want to do this stuff myself is that this is my only car, and I need it to work for a while yet. Spending £100 or so on labour seems like a good deal to have a car that still works afterwards 😂

I also don't have access to a driveway at the moment because I'm still a student, so it's uni car park instead, which is fine, just a little annoying since the pressure is still there to have it moved again by Monday. I'm also pretty physically weak as well - I'm used to contorting my hands into shapes an octopus would be jealous of for electronics work, but muscling things into alignment is not my forté.

It depends how easy the engine mounts are I guess. I'll watch Involvod's video on it again, and see if I'm feeling up to it. Some final questions for now:

1) Which side would you recommend I start with, right or left?
2) How much support do the engine/transmission need? I seem to remember hearing a ratchet strap around the engine is sufficient, but does the trans need supporting by a jack as well while doing this?