2.3L ('83-'97) Knocking @ Idle with AC on

[ForgedCrank]

Ok tell me what you guys think...

1994 2.3, 5 speed. Actual mileage 87K

With the thing idling, everything is normal. When I turn on the ac compressor, I start getting a knock that sounds like it is either coming from the front half of the transmission or the clutch area.
Leave AC on and press clutch pedal, noise goes away.
Release clutch pedal and turn OFF ac compressor, noise goes away.
The knock is only audible @ idle with AC on and clutch engaged with trans in neutral.
I'm kinda at a loss with this one, it' snot making sense to me unless I'm hearing a main bearing noise that sounds like its coming from the transmission?
And no, that is not an exhaust leak. That is the knocking. The video makes it sound even louder, but it is pretty loud in person too.
Opinions?
(Don't make fun on my epileptic video skillz)

 

[ForgedCrank]

I'm starting to think I may have asked a dumb question...

 

[scotts90ranger]

I have very few vehicles with A/C or at least working A/C (4 of 6 have A/C and only the wife's car works...) and never in a Lima... I'd have to guess it's likely normal if everything works

 

[ForgedCrank]

I have very few vehicles with A/C or at least working A/C (4 of 6 have A/C and only the wife's car works...) and never in a Lima... I'd have to guess it's likely normal if everything works

I don't think the AC has anything to do with it necessarily. I think it's just adding a load and low RPM that normally isn't there and is making the condition known as a result. I want to believe its a clutch/throwout bearing type issue, but based on what I've been reading, sounds like this M50D is known for problems with the input shaft, mostly the primary bearing up front there. I'd just drive it til it becomes an operability problem, but I'm worried about doing more damage if I let the happen. Right now I recon I'll be dropping the transmission and see if I can find someone reasonably local to me that might be willing to overhaul it for for beer and ammo money. I can't put transmission shop money into this thing so... if you know anyone in Indiana that'll do it as a side job let me know. I've never done a manual transmission and I don't have a press or any of that crap.
Major blow to the budget Ranger project for sure

 

[scotts90ranger]

Even if it does wear prematurely on the input shaft, the input shafts are readily available... It could really be as dumb as worn out clutch friction disc isolation springs or whatever they're called... I've rebuilt my M5OD twice, it's not too bad but a press does help but it doesn't stop you from changing much, the hard part is a deep enough puller for the rearmost gear...

The valvetrain on these is known to be loud, with a little extra load I could see that being louder.

The bottom end can handle like 350hp stock aside from the cast pistons and these don't normally have oil pressure problems other than the first couple years of the aluminum oil pan where the sealant got to the pickup tube so unless someone ran the thing low on oil all the time or never changed it I wouldn't worry too much about it... you now know the top end is solid

 

[ForgedCrank]

I don't think the AC has anything to do with it necessarily. I think it's just adding a load and low RPM that normally isn't there and is making the condition known as a result. I want to believe its a clutch/throwout bearing type issue, but based on what I've been reading, sounds like this M50D is known for problems with the input shaft, mostly the primary bearing up front there. I'd just drive it til it becomes an operability problem, but I'm worried about doing more damage if I let the happen. Right now I recon I'll be dropping the transmission and see if I can find someone reasonably local to me that might be willing to overhaul it for for beer and ammo money. I can't put transmission shop money into this thing so... if you know anyone in Indiana that'll do it as a side job let me know. I've never done a manual transmission and I don't have a press or any of that crap.
Major blow to the budget Ranger project for sure

I figure my plan at this point (still pondering) is to drop transmission, check out the clutch parts and if needed, replace the clutch, PP and flywheel, slave/throwout and pilot... put it back together and see what happens. If its still a wreck, then I'll get a boneyard trans and rebuild it over the winter. I don't know if I'm capable on this job though. I've done more than several automatics, but I split a gearbox like this once and to me it was like a washing machine... it never goes back together right and winds up out on the road for trash pickup two days later.

 

[lowspeedpursuit]

I missed this thread until now. Mine does the same thing.

My noise has survived multiple pilot bearings, TOBs, ISBs, and a full trans rebuild chasing down a different, non-AC related noise.

It's either normal, "normal" for an old, tired engine under those particular conditions, or my pressure plate rattles.

It doesn't technically happen whenever the compressor's on, it happens when the idle drops as a result. I don't know why the ECU isn't able to compensate more effectively. I manually bump the idle up with the throttle screw during the summer. I know that's not what that screw is supposed to be for on EFI motors, but them's the breaks.

 

[ForgedCrank]

I missed this thread until now. Mine does the same thing.

My noise has survived multiple pilot bearings, TOBs, ISBs, and a full trans rebuild chasing down a different, non-AC related noise.

It's either normal, "normal" for an old, tired engine under those particular conditions, or my pressure plate rattles.

It doesn't technically happen whenever the compressor's on, it happens when the idle drops as a result. I don't know why the ECU isn't able to compensate more effectively. I manually bump the idle up with the throttle screw during the summer. I know that's not what that screw is supposed to be for on EFI motors, but them's the breaks.

you've really got me twisting a bit on this. I unfortunately tend to be a bit overly compulsive about stuff like this, I don't mind broken vehicles, as long as they are at home. plus it drives me nuts knowing something isn't right. I don't know if I should just drive it til it quits or tear it down and do what it takes to make it right.

 

[scotts90ranger]

I figure my plan at this point (still pondering) is to drop transmission, check out the clutch parts and if needed, replace the clutch, PP and flywheel, slave/throwout and pilot... put it back together and see what happens. If its still a wreck, then I'll get a boneyard trans and rebuild it over the winter. I don't know if I'm capable on this job though. I've done more than several automatics, but I split a gearbox like this once and to me it was like a washing machine... it never goes back together right and winds up out on the road for trash pickup two days later.

On my last rebuild I watched a U tube video of a guy tearing one apart and putting it back together (it was a core so he didn't put new parts in), these transmissions are pretty simple and if you're just doing bearings for the most part pretty simple and you don't need to rip the whole thing apart... After that one I did the ZF5 from my '97 F350 and that was much more of a pain in the rear since the whole rotating assembly came out and had to be put back in as one unit and weighed a measly 160 pounds if I remember right... The M5OD comes apart one piece at a time and you can lay it out...

 

[lowspeedpursuit]

you've really got me twisting a bit on this. I unfortunately tend to be a bit overly compulsive about stuff like this, I don't mind broken vehicles, as long as they are at home. plus it drives me nuts knowing something isn't right. I don't know if I should just drive it til it quits or tear it down and do what it takes to make it right.

I feel you. I hate shit that doesn't make sense, and leaving things half-done, as much as the next guy. At the same time, there are only so many hours in the day.

For me, having been inside the trans and the noise going away with the clutch in makes me comfortable enough with the idea that it's related to the clutch itself. I'd engine swap away from the NA 2.3L before I considered rebuilding this motor trying to chase it down. If I replace my clutch or swap my motor at some point, I'll follow up.

Your noise and mine aren't necessarily the same. I would at least check the trans if it makes you feel better. You can drop it, pull the top cover, and see if there's anything catastrophically wrong towards the front pretty easily. Actually taking it apart is a pain in the ass, but half the work is just the output shaft stake nut and rear bearing.