'95 W124 E280 Overheating

[SNST]

Is there an established procedure routine for pressure testing the transmission fluid cooling pipes to check for corrosion?
I'm trying to keep costs down for next 3 months for cash-flow reasons - short on cash, long on time, so the backflush option is appealing!

 

[television]

With the rad and engine warm or hot you can feel with your hand if the heating or cooling is uniform across the whole area surface, they should be warmer at the top, but uniform across the width

 

[grober]

Is there an established procedure routine for pressure testing the transmission fluid cooling pipes to check for corrosion?
I'm trying to keep costs down for next 3 months for cash-flow reasons - short on cash, long on time, so the backflush option is appealing!

If cash is the problem then by all means try a back flush. No doubt you could rig up some sort of pressure test for transmission heat exchanger integrity, but this would only tell you if its leaking. It wont really tell you how corroded it is. Perhaps a radiator specialist could help- a re-core might be possible and cheaper than a new rad?

 

[SNST]

I've had one quote for a re-core from company with a good reputation --£150
Almost the same as a new "best" one from Eurocarparts.

I'll try backflushing soon & report back.

Is there a problem using pressure washer to clean muck from the fins?

 

[television]

I've had one quote for a re-core from company with a good reputation --£150
Almost the same as a new "best" one from Eurocarparts.

I'll try backflushing soon & report back.

Is there a problem using pressure washer to clean muck from the fins?

Take care when doing it, the copper becomes brittle with age and you could force insects etc right in. An engine cleaner and paintbrush could be much kinder.

 

[SNST]

Ok.. Time for an update.

No sign of external fin clogging, so left that issue.

I borrowed an infrared thermometer and ran a traverse over the radiator.

With increased revs, there was a good close temp distribution across top and bottom halves with at least a 10C differential between the halves.
Makes me think the radiator is OK.

Low revs had bigger differential across the headers and top/bottom halves which reduced markedly with revs.

Also noted this morning that the heater didn't warm up for the first 20 miles. Then I took a steep hill with revs up and straight away the heater came to life.

I'll start with a water pump & post again later.

Simon

 

[SNST]

Preparing for the pump replacement in next couple of days:

Pump is attached with cap head screws/bolts.
I have seen mention of possibility of stripping mounting bolts.
Is this likely? What sort of torque is needed to crack them?

Is there benefit in having the block warm?

Any other sensible preparation you can recommend?

 

[kth286]

You will need the slimmest quarter inch extensions with slim wobblies and socket, or you will not be able to access the two inner bolts.

Lots of dismantling to do, and you will need new seals for the coolant pipes across front of engine, and for the pipe that runs back from pump, alongside of engine, to oil cooler heat exchanger (part of base of oil cooler).

 

[SNST]

Interestingly, the fan passed the carrot test. Plenty of peelings & seemed to not slow the fan down. (On reflection, I didn't try long or hard enough but the engine was getting coated with carrot!)
I then had someone turn off the ignition when running at 110C indicated. The fan ran on for maybe 2-3 seconds.
I read somewhere of using a newspaper. That easily stopped the fan at mid revs & hot. I could then hold the fan as I tried both high & low revs & as the temp rose. Very little force was involved. I could hold it resting my little finger on a blade!

This suggests that whilst the carrot test might work, the coupling might not be "coupling" as well as it should.

Any comments?

Are there different quality couplings available? I see ECP are about £43

 

[grober]

The mercedes viscous coupling is normally made by SACHS. If that's what ECP use then fine.

 

[markheaney2]

overheating

i had exactly the same problem on my 124 it turned out to be a blocked radiator

 

[SNST]

Progress so far...

Water pump replaced. Photo attached shows impeller has virtually disappeared. (I have been using a 25% antifreeze/inhibitor for the last 3 years!)


Viscous coupling replaced. ECP use OTSA (Turkish). The first one is not right & they are changing it. I think the bimetallic strip is not pushing the pin down when cool, so constantly engaged.
In this case, I would have done well to spend more elsewhere ( Sachs, as Grober suggests!)

Looking on the web, I've finally found the workings: The pin moving out (hot) allows the silicone fluid to flow into the chamber with the drive plate, equalising the levels in the chamber and reservoir, increasing the coupling between the drive and driven plates. When it cools, the pin is pushed back in by the bimetallic strip, closing the orifice and stopping fluid entering. Centrifugal forces gradually encourage the fluid to leave the chamber and return to the reservoir in the driven assembly, leaving a residual amount of fluid in contact with the drive plate which provides the resistance we can feel when the engine is stopped and keeps the fan turning slowly when the engine is running cool. I hope that sounds reasonable.

I have found a Torx t20 key is just right for locking the pulley. I've just managed to insert it (long leg at about 4 o'clock!) with all the cooling pipes in place, just removing the shroud, fan and belt. The small diameter metal coolant pipe across the front does get in the way, so I've been lucky.
Less than 1 hour should see the job done.

The overheating seems to be solved, but the coupling means a lot of noise above 2000rpm and big power loss above 3500rpm.

 

[kth286]

Only use Merc coolant fluid on a 50%/50% basis with ionised water. It is ph neutral and will protect your new pump.

The viscous fans must always be stored/carried in a special orientation - upright only.

 

[SNST]

Can anyone tell me whether approvals of coolant to MB Spec DBL7700.20 / 325.0 are a good guide?

Yes, ECP have a label with storage orientation shown on the viscous coupling box & they assure me that their procedures do take note of this.

Anyone installed a Sachs/MB viscous coupling recently?
When cool, ie disengaged, when does the fan noise become noticeable with the bonnet up? 2000rpm?
Can the fan be stopped from 2000rpm with rolled-up newspaper?

 

[balge59]

hi
went through a cooling problem myself recently - http://forums.mercedesclub.org.uk/showthread.php?t=69174
opposite of your problem and hopefully you aren't missing any important bits!
Point being, my car has viscous fan too and yes, it spins up straight away even at tickover it is roaring a bit and shifting plenty of air. As to 'carrot test' well, mine knocked a stick out of my hand at tickover when I tried it! It certainly isn't new & I can't tell what make, but I didn't try to stop it at all!
At standstill the fan can be pushed round with a finger, but does not 'freewheel' at all.

HTH

balge

 

[television]

I am pleased that you are getting somewhere now and the main problem is done with

 

[SNST]

Thanks Balge, I don't know why the search words I used didn't highlight your thread.

2nd ECP unit is much less intrusive, so I'll assume it is a good one, even though I can't stop the fan at idle with a newspaper, let alone 2000rpm!

I'm trying the Comma G48 antifreeze (MB spec. DBL7700.20 325.0 approved).....I'll report in a few years when the pump fails!

All running well so far. Thanks to all for your input.

 

[SNST]

Next update...

I decided the fan was not decoupling effectively so that coupling went back.

A GSF unit next. Box says Flusser. No significant web presence, though.
The fan roared for 30 seconds then quietened down.
As a test, I can stop the blades easily from idle.
It cuts in audibly when the temp gauge is approx 90C. Maybe a little early, so I'm going to try to measure the hub temperature when it engages.

Anyone know what temperature the hub should be?

Otherwise, all seems smooth, quiet and thankfully cool.

 

[balge59]

Good one!
Your fan seems to be less 'firm' than mine but it must be in the right range for your motor, I imagine the action is fairly variable from one unit to another!

Do you think the operating temperature of these units can be adjusted by fiddling with the bi-metallic strip? As said, mine seems to be driving virtually all the time if it was a bit slacker it might help the car warm up quicker.

Cheers!

 

[television]

The visco fan relies on the stream of hot air through the rad, when the rads get blocked the fans often will not cut in, they all cut in at just over 85c around the same time as the thermostat opens, you can hear the audible click as they cut in