Auto Gearbox 280GE Whinning Issue

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kman
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Hi Guys.

Have a 1988 2.7L Gwagon 280GE  AUTO. Was sitting in a field for 3 years and have spent the last year renovating it. I've been very lucky to find a great mechanic (and this amazing forums) who has gotten the truck running great with a lot of hard work/phone calls. We are in the caribbean. Tough to find a good mechanic.

We are onto the gearbox and going to pull the transmission;

1. There is a whinning noise when we first drive forward off in1st/2nd gear. When it hits 3rd gear it stops whinning. The best way to describe this noise is it sounds like it's going in reverse (this same whinning noise)...

2. It also feels the gears slip sometimes

3. He feels we may be starting to drive in 2nd gear (not starting in 1st at all) and can only hit 40mph max..

 

Guys is there any electrical components to these transmissions?

We have replaced the kick switch.

Guys any guidance or help is very much appreciated for us as these forums have been great for us..thx guys..Tony

neilmarton
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Re: Auto Gearbox 280GE Whinning Issue

Hello Kman,

Good to hear you are finding your way around the little truck and making progress with its health !

As you know I am not the best when it comes to engineering and mechanicals but I was told once that the auto box is controlled via the vacuum system so might be worth checking you have no blockages or breaks in your vacuum pipes ?

Best of luck,

Neil

kman
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Re: Auto Gearbox 280GE Whinning Issue

Hi Neil great to hear from you. Hope the xmas/new year went well...

Thx for above as always (interesting)...any direction on were i might find a diagram/layout of vacuum system??

Have manual but nothing there..Also forget to mention we replaced transmission fluid before xmas..

Neil always appreciate the advice/direction and yes the little truck is running well with all your guidance/help/great to drive..last item i feel now is figuring transmission...thx again man..tony

Russ280
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Re: Auto Gearbox 280GE Whinning Issue

It's supposed to start in 2nd. You can force it to start in 1st by selecting it manually or flooring the throttle to make it kick down.

 
Slipping is not good but I'd start by replacing the fluid and filter. You need to drain the torque converter separately. You access the drain plug through the bell housing.
 
If it's of unknown history I would suggest replacing the fluid twice. When I've done this I use some cheap D3 fluid, run it for 20 or 30 miles and then replace with good quality fluid.
Arnie
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Re: Auto Gearbox 280GE Whinning Issue

There are no electronics in these transmissions.

Are you sure the whine is not coming from the transfer case?

kman
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Re: Auto Gearbox 280GE Whinning Issue

Thx Russ & Arnie appreciated..

 

Very interesting it should start in 2nd...will leave as is..thx for heads up with this..

When you mention filter and it may sound stupid is there a filter on this transmission to replace???

Would you know what kind of fluid goes into the torque converter when drained to replace?

Any ideas why i am only hitting 40mph max? I have replaced all throttle/linkages, fuel pump recently??

Thx for tip on replacing fluid a few times...

 

Arnie any idea what to look for in transfer case to know if it causes whinning??

Would Neil above have a point on vacuum leaks/blockage?

 

Guys i do appreciate your valuable advice and direction...really trying to get a grip of this final renovation/transmission...thx guys t

Russ280
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Re: Auto Gearbox 280GE Whinning Issue

Once you remove the gearbox sump the filter is right there, it will be obvious.

 
The torque converter uses the gearbox box fluid but just draining the gearbox will leave old fluid in the torque converter.
 
When you say it will only do 40mph what are the engine rev's?
 
If it's doing more than say 2200 the gearbox clutches are slipping. Not good. Unlikely that just replacing the fluid will cure this.
 
If however the engine will only rev to 2200 that indicates a problem with the engine.
Russ280
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Re: Auto Gearbox 280GE Whinning Issue

Maybe a dumb question but are you sure it's in high range?

Arnie
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Re: Auto Gearbox 280GE Whinning Issue

As Russ mentioned, check the transfer-case lever is in S position for 2-wheel drive, high-range.

I know others have made this mistake, wondering why the engine revs are so high.

 

While at it, change the oil also in the transfer-case, It should be a GL-4, gear oil, SAE-80W or one of the 75W-80 or 75W-90, but NOT a GL-5 type. (must not mention API  GL-5).

 

... and most importantly, don't forget to grease the 3 prop-shafts (3 grease-points on each: Universal- joints at each end and  and extending spline in the middle), and change the diff oil, too. This should be a GL-5 type, Hypoid or EP  oil, nominally SAE-90W or one of the 75W-90

(http://www.widman.biz/uploads/Transaxle_oil.pdf)

 

For the auto-transmission:

if you feel a reaction within a second of moving the auto-transmission lever from P or N   to   D or R, then the gearbox is likely fine.

But change the oil and filter. It's exactly the same as in any Mercedes car of that vintage (W123, W124 etc) and very simple to do.

 

 

kman
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Re: Auto Gearbox 280GE Whinning Issue

Thx Arnie & Russ very very helpful.

Yes this is an issue we resolved early on with making sure what the letters meant on the drive. We are definitely in high range "S".

 

We have done a lot of work on the engine replacing /injectors/fuel dis/airflow/cables/hoses and to be honest when i place the truck in drive (D" as you mention above it feels like it wants to take off like a race horse. Really feel the power is there but when it hits 40mph i really feel the engine is saying lets go faster but the transmission OR something is saying hold on here i am not quite ready....

I did a quick test:

1. Drove the truck in gear #3 and it drove very strong with this whining noise close up to 30- 40mph.

2. When i changed it up to gear #4 the whinning noise stopped but like above the truck wants to take off like a race horse (power there) but just not been allowed once it hits 40mph

They only initial work we have done on the transmission is replace the fluid but we are really trying to get into the nitty gritty of it now. We didn't change the filter and hate to say we were told this could be cleaned out (true???) ?

Thx for heads up on convertor and oil types.

***this may sound strange but i hear a "air noise/air gushing/maybe leak" just from behind the middle of the dashboard when driving. I closed the air vents and turned off the radio (because it sounded like a radio station that wasn't tuned in). NOW we have replaced all linkage from the front of the truck firewall to the main engine/throttles BUT nothing replaced behind this firewall leading under the truck/transmission if this helps....Maybe nothing too..

Guys THANK YOU...THANK YOU...tony

markhowes
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Re: Auto Gearbox 280GE Whinning Issue

Bear in  mind that I know next to nothing (that's why I'm always on here asking for help) - but doesn't this sound as though the car has gone into "limp home mode"?

 

 

Russ280
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Re: Auto Gearbox 280GE Whinning Issue

What rpm is it doing at 40mph?


Mark,
It doesn't have a limp home mode.
 

markhowes
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Re: Auto Gearbox 280GE Whinning Issue

Oooops blush

kman
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Re: Auto Gearbox 280GE Whinning Issue

Thx Russ and Mark.

 

Russ i can't tell rpm as it has old dials on the dash which just show MPH, water/oil temp..

To be honest when i hit 40mph its not revving high. The truck naturally builds up speed thru the gears and it just seems the engine wants to go faster (power there) at 40mph but transmission stopping it...or something...you must think i'm nuts how i explain this :)

Thx guys...tony

scouse g
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Re: Auto Gearbox 280GE Whinning Issue

i recently had someone ask me that their g wouldn't go fast, turned out to be brakes binding, had u checked brakes and will it roll freely ?

Arnie
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Re: Auto Gearbox 280GE Whinning Issue

If it's binding brakes, then Brakes International can supply replacement pistons and seals for the calipers, or complete refurbished calipers, for relatively little. However, I would go for the seals and pistons, if your calipers are in decent cosmetic shape. (The refurbished calipers are nicely galvanised and shiny, but most are heavily pitted from previous rust)

Have you checked all the linkages and vacuum switches for the throttle, as these then connect and control the gearbox? The vacuum affects the quality of shift and the throttle linkages, the shift points. Also, check the kick-down solenoid valve, which will keep a lower gear ratio, if not working properly or stuck.

The brake servo is on the other side of the fire-wall so ensure that you have no vacuum leaks (hissing).

The vacuum lines are made of nylon and quite tough, but the connections are rubber and they deteriorate with age and eventually leak. Ensure that the vacuum system, valves and switches are all checked and renewed if necessary. Then, tighten the throttle linkages- particularly from gearbox to engine -  to remove any slack in the cables, as this will affect the shift-points.

The gearbox oil filter is not expensive and is a paper-element type, which is not intended to be washable  / re-usable.

if none of this works, then perhaps a visit to a transmission specialist may help, if indeed there is an internal fault in the gearbox. It might be why the car was abandoned in the first place?

 

 

 

 

 

kman
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Re: Auto Gearbox 280GE Whinning Issue

Thx guys all very helpful.

The first thing we did when we picked up the truck was to take apart the brakes/clean/shoes in great condition and replace cylinders as they were leaking. Seems all good on that end. Truck is easy to push forward so moving smoothly.

The Diff oil was changed (checked diffs were not on) recently along with the transmission BUT as mentioned earlier we will look at converter to drain and maybe change trans oil again.

The filter was explained to me in this truck to be steel? and it was removed/cleaned out and placed back in. Would this be true?

We have replaced linkages/tightened from the firewall back to the engine BUT i do feel there may be other linkages from the firewall back to the gearbox??? Would anyone have diagrams of this or direction what to look for?

I also feel a leak maybe be possible in the vacuum. Would anyone have a diagram of this or how to test it/diagnos it. were do the vacuum hoses run from and how many?

****We have a manual but none of the above are shown specifically...

I can't wait to get to the end of this..its been a long road (year) but i do appreciate everyone's help/advice as it's made it alot easier...thx guys tony

Arnie
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Re: Auto Gearbox 280GE Whinning Issue

The transmission oil filter is encased in a flat metal can, but it is paper inside.

If you intend to flush the oil once or twice, don't worry about the oil in the oil in the torque converter housing, it will mix with the new oil as it gets pump around the gearbox and the small quantity will get diluted out.

The rear wheel brake  cylinders will rust, leak and need to be replaced as you've done, but check the front calipers too, as the pistons can stick, if their weather-boots are damaged.

There is a link for the throttle to the top of the engine valve-cover, where it joins a mechanism with a limit switch and vacuum valve. There is also another bowden cable from here that connects to the gearbox.

There should be a lot of information on-line for the Mercedes W123 saloon, which used the same engines and systems as your G-wagen:

http://www.benzworld.org/forums/w123-e-ce-d-cd-td/1597891-diy-w123-transmission-diagnose-adjustment-722-a.html

 

 

 

 

 

 

 

 

kman
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Re: Auto Gearbox 280GE Whinning Issue

My gut is telling me Vacuum...Vacuum leaks, split or even disconnected hoses. These also affect the operation of the gearbox???

We done a tremendous amount of work to this little truck to get it back in action and just haven't really hit the gearbox/Trans without getting advice/direction from you guys and to safe working in the dark....

 

Is there a way/diagram we could use to trace them all and maybe find some of the rubber connectors perished/hoses.

My gut feeling..tony

Arnie
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Re: Auto Gearbox 280GE Whinning Issue

there are some diagrams in the above link and some more info here.

https://mercedessource.com/problems/transmission/does-your-automatic-transmission-really-need-replacing

It might be worth investing in a mercedes WIS CD set with ECP (about £20 on ebay) as this will give you a lot of the diagrams and part numbers you require. or register here

http://www.service-and-parts.net/dcagportal/DCAGPortal/portal.action

 

 

 

 

 

 

 

 

kman
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Re: Auto Gearbox 280GE Whinning Issue

Guys i want to thx everyone for their advice as always...

I will be taking all your directions and going through all the hoses (vacuums), linkages (again) and after reading a link above replacing the vacuum modulator (in anyways) to try to at least pin down any issues here..

I will keep you posted in the hope i can help others who may come across the same issues..thx again guys and speak soon..t