Volvo 4400

[antz]

Hi all, further to my previous post, I thought it may be important to add the following details (and hope for comment..)

The transmission oil does not appear to be getting hot. It has been changed and is clean. I have reconnected the factory trans temp gauge and it seems to correspond to an ir thermometer both at the sender location at at several other locations around the transmission, and I am happy that the oil is not overheating.

The transmission 'drops out of gear' at operating temp, approximately 68c, at idle.

The transmission will disengage at idle, however, does engage fully with some throttle. There is no lack of power - It engages with an obvious thump

This furthers my thought that the transmission itself is not cactus. Is there some sort of valve that will return to tank or similar that may be effected when hot? Perhaps a spring, relief etc?

I have (a while ago) changed the filter, and cleaned the pickup in the trans, and not convinced that either of these are the problem.

Thanks in advance

 

[angus005]

I have an ex military Volvo 4400 and would like to know the availability of spare parts.

 

[OzDozer]

Volvo BM 4400 owners can acquire a manual from the site below. The manual is an electronic version, emailed to you. I have dealt with this site previously, they provide what they say they will provide.

Download VOLVO BM 4400 WHEEL LOADER Service Repair Manual

Download VOLVO BM 4400 WHEEL LOADER Service Repair Manual VOLVO BM 4400 WHEEL LOADER SERVICE AND REPAIR MANUALCOVERS ALL MODELS & ALL REPAIRS A-ZTHIS IS NOT GENERIC REPAIR INFORMATION! IT IS VEHICLE SPECIFIC. THIS IS THE EXACT SAME MANUAL USED BY TECHNICIANS AT THE DEALERSHIPS TO MAINTAIN...

www.heavy-equipmentmanual.com

For old Volvo equipment parts in Australia, I have found the following company quite good for older Volvo parts. I have a client who owns a BM 4400 locally (in the wheatbelt of W.A.) and I found a new water pump for his 4400 from these people, they had one on the shelf.

Just keep in mind these BM 4400's are 40 yrs old and older, so you're not going to get any help from Volvo.

Earthmoving & Construction Equipment Parts

Supplying Genuine and OEM Quality Replacement spare parts for the earthmoving equipment market is our business.

www.sourcemyparts.com.au

Angus005, I would imagine you're well placed to acquire BM 4400 parts in the U.K. Look to old Volvo suppliers in Sweden, and to MOD surplus dealers in the U.K.

 

[antz]

I have a hard copy of the workshop manual, both the general one, and the transmission. Neither of them are really any help, they only run through removal and rebuilding of the trans, not any troubleshooting.

I can confirm Source My Parts are good to deal with, and usually a lot more affordable for parts than the local Volvo CE dealer.

 

[antz]

I have started looking at the solenoids. There is some suspect wiring to repair which was giving me a low ohm reading on the S1 solenoid (compared to the others of the same brand / type), and as this solenoid always has power when in any gear, this may have something to do with my problems. Process of elimination i guess. The coil on this also has a crack so im going to swap it with the 4th gear solenoid. If anyone can point me in the direction of a new coil that would be great. Currently awaiting a price for a new one from supplier. I would also be grateful for any tips on removing an
d cleaning the valve body, looks as though I will have to remove all the coils to get it out. As funwithfuel pointed out, the wiring insulation is not in a good way after 40 years. I have already had to make a new harness from the cab to the solenoid bank.

I ended up pulling the rear wheel and the trans filter housing to get access, it is way to painful without doing this.

 

[antz]

So the investigation has continued further, and i think that there is a wiring issue with the gear selector, which may explain why 4th gear has never worked (always stayed in 3rd when either 3rd or 4th was selected). This leads me to wonder if there was power going to a solenoid that it wasn't supposed to, could this cause the low pressure in the transmission, bleeding off pressure somewhere when it shouldn't be?
The investigation continues....

 

[antz]

So wiring has been fixed, I now have 4 gears however I still have the same drive issue. Transmission and converter pressures are in spec at wot as per the manual however at idle they drop away considerably, getting worse as the oil warms up. Main pressure is 185 psi at wot, but drops to 60 psi at idle, and that is when the trans drops into neutral.

Im guessing the torque converter is no good and dropping pressure when the oil warms up?

Any thoughts??

 

[OzDozer]

Antz, I'd be examining the condition of the pump before tearing into the transmission. Also, it could be an internal o-ring partly blown that is dropping the pressure. An o-ring under a valve body?

 

[antz]

So the only external pump is for the steering and hydraulic. I am absolutely convinced that the trans isn’t buggered, but I can’t work out why it would drop pressure at low revs, but be fine at full revs. Machine is too old to warrant removal of the trans but I’d sure like to work out what the problem is. Next step will be to remove the valve body / solenoids and do what I can to clean it. That will also involve making another loom, the factory wiring is not in a good way when disturbed

 

[OzDozer]

The symptoms indicate that adequate pressure is capable of being produced when the revs are up, but is being lost when the revs are down.

That indicates leakage - either via excessive pump clearances, or by a leak in the system that is supposed to hold adequate pressure at low rpm.

 

[antz]

It seems like it is bleeding pressure somewhere, I just don’t have the knowledge to work out exactly where at this point. I can’t believe that the trans is buggered if it does what it is supposed to do at full revs, and pressure readings are ok.

 

[antz]

And further to your comment ozdozer, what pump would be ‘leaking’ ? Only pressure I see is from converter or lube pump, and low lube pump pressure wouldn’t cause the symptoms as far as I know.

 

[OzDozer]

There should be a main transmission pump supplying pressurised oil to the transmission and torque converter.
If it's a powershift transmission, it requires high oil pressure to keep the clutch packs engaged (as evidenced by your "185psi" pressure reading).
This is not normal lube oil pressure, lubricating oil is normally bled off from the main pressure line/s at lower pressure.

If the required high oil pressure drops, the clutches either slip, or the system has pressure-drop protection, and it drops into neutral to protect the transmission/converter from damage.

 

[antz]

Here are some pictures from the manual. The main pump is within the torque convertor assembly (I think). There is a seperate lube pump housed within the transmission (I think).
The third image gives me more food for thought re the solenoids and possible problems when one or more warm up.

 

[OzDozer]

Well, if you have the transmission manual, you're all set. The descriptions and schematics are good and the instructions are clear, so it's only a matter or reading and re-reading until you have a good grasp of how it all works.
It is often difficult to figure out where pumps are located, though, especially when they're positioned internally.

 

[antz]

The manual is ok for pulling the transmission apart and putting back together. Unfortunately, the only diagnostic information it includes (other than the pressure tables) is "If it's f*#ked, replace it", and that isn't terribly useful for me.

 

[antz]

So having removed the valve body,cleaned, new seals & o rings, replaced a couple of solenoids, and rewired everything, Im back to square one.

If anyone has any suggestions of any wreckers any where that would be appreciated.