W124 200TE Auto - Vibration, Heater & Radiator questions

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Creamy

New Member
Joined
Aug 22, 2008
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14
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200TE Auto Estate, 300D Auto Estate
Hi,

I've just acquired a '91 200TE Auto Estate. As I paid little for it, I am happy to spend a bit on it to tidy it up a bit. The bodywork is good for its age (a bit of normal wheelarch stuff) and at 170k I hope it's got a bit of life left. I would like some advice from members regarding a couple of problems with it:

1) Vibration - between 60 - 90 MPH there is some vibration which does not appear to be the front wheels, although I can feel it a bit through the steering. I have checked tyre pressures, had all wheels balanced and tracking adjusted. I have also just changed the front propshaft coupling as this was completely shot, and wouldn't have helped things. Each of these actions has improved things, but the vibration is still there. Before I go back to have the wheel balance double-checked, does anybody have any other ideas?

2) Heater - I can't get hot air from the heater (no aircon fitted). I've seen lots of discussion about the duo-valves failing and ONLY getting hot air, but not my symptoms. Checking for power, I see 13.5v on the duo-valve centre connector, but nothing on the other 2, irrespective of the heater controls. The auxiliary pump has 13.5v on the +ve connector, but apparently no earthing on the other. Connecting directly to the battery has confirmed that the pump works. I'm guessing that if the pump worked full-time, then I would get continuous hot air from the heater? All fuses appear to be OK (and there's power at the valves and pump), so should I be looking at a controller circuit, or maybe simply an earthing lead somewhere?

3) Radiator - Although only 2 years old, the radiator has a leak at the top of the matrix. Previous owner put radiator sealant in which fixed the problem briefly, but it continues to blow. It could simply be that the radiator is a duffer, but does anybody have any advice? I have not pressure-tested the system yet, but with the cap off, it does not appear to blowing from the engine - no signs of oil/water mix anywhere. I don't want to splash out on a new radiator if it's going to blow again.

Any help with these would be appreciated.

I'm still undecided whether to keep it or sell it on (and possibly buy a newer one with lower mileage, maybe diesel) - any thoughts / advice?

Thanks,

Creamy
 
1) Vibration - between 60 - 90 MPH there is some vibration which does not appear to be the front wheels, although I can feel it a bit through the steering. I have checked tyre pressures, had all wheels balanced and tracking adjusted. I have also just changed the front propshaft coupling as this was completely shot, and wouldn't have helped things. Each of these actions has improved things, but the vibration is still there. Before I go back to have the wheel balance double-checked, does anybody have any other ideas?

Centre bearing of the prop shaft maybe?

2) Heater - I can't get hot air from the heater (no aircon fitted). I've seen lots of discussion about the duo-valves failing and ONLY getting hot air, but not my symptoms. Checking for power, I see 13.5v on the duo-valve centre connector, but nothing on the other 2, irrespective of the heater controls. The auxiliary pump has 13.5v on the +ve connector, but apparently no earthing on the other. Connecting directly to the battery has confirmed that the pump works. I'm guessing that if the pump worked full-time, then I would get continuous hot air from the heater? All fuses appear to be OK (and there's power at the valves and pump), so should I be looking at a controller circuit, or maybe simply an earthing lead somewhere?

The plug on the back of the centre panel sometimes comes lose and can cause the heating not to work.

3) Radiator - Although only 2 years old, the radiator has a leak at the top of the matrix. Previous owner put radiator sealant in which fixed the problem briefly, but it continues to blow. It could simply be that the radiator is a duffer, but does anybody have any advice? I have not pressure-tested the system yet, but with the cap off, it does not appear to blowing from the engine - no signs of oil/water mix anywhere. I don't want to splash out on a new radiator if it's going to blow again.

Ah, the sealant used, has this clogged up the duo valves? Back to the radiator, I would purchase another radiator, the likelihood of it blowing again is slight. I may be wrong though. Is the rad cap the right release pressure (10psi).
 
front wheel vibration- try renewing/testing the steering damper--small shock absorber on the steering linkage---about £30 and a simple DIY.
 
front wheel vibration- try renewing/testing the steering damper--small shock absorber on the steering linkage---about £30 and a simple DIY.

This comes up regularly. I've never changed one. But it strikes me that the function of the damper is to damp and not to stop vibrations. Vibrations shouldn't be there in the first place - it implies there's some compliance there that shouldn't be

Almost inevitably front end vibration seems to be wheel & tyre-related. I had a set of new Contis fitted to refurbished wheels, balanced & fitted to a car the other day and the steering wheel vibrated at 70 mph. Had the wheels rebalanced and the vibration went away. I must ask how much out they were because the effect was very noticeable through the wheel

Nick Froome
www.w124.co.uk
 
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My new front steering shock absorber stopped my tramlining on the motorway, it was just as smooth with and without it.

I fixed a long running vibration problem by replacing the propshaft doughnuts.

Dave!
 
Ian, you were spot on with the heater. Whipped out the control panel, reseated the plug and the pump and duo-valve came to life. Both sides of the valve click, which is reassuring. Doesn't seem to get very hot from the vents, but I wouldn't be surprised if the whole system needs flushing, especially if there's been no pump to push water through the heater matrices for a while. May even be an airlock which clears when I drive to work tomorrow (well, I can only hope!)

The steering damper suggestion sounds like another job for the list. I certainly get far more camber effect than on my Laguna, and some steering judder over potholes. Not what I would expect from a large (albeit old) Merc.

Any idea where I might be able to get a cheap thermostat cover (preferably new)?
 

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