Busted 6.9 cooling system

[Styria]

Well, it did have to happen to myself and Gleaming Beauty at some time or other - the time was last Saturday, coming back from Michel's - and the dreaded thing did happen. No, it wasn't the motor or gearbox that blew up, but the cooling system.

Cut a long story short (to be accompanied by pictures in due course), for some reason that I have not yet established, the cooling fan got "all wobbly" with the result that some cooling blades broke in the process of destroying what really was a brand new core installed at the time of the valve grind and de-coke.

This happened on a very busy main thoroughfare, but I was lucky on two counts - there was a bus stop cut-out in the main road (that's what I thought it was) and there was an open driveway to a private yard that sported an extraordinarily long water hose.

Initially, I thought that the car was overheating, but no such luck. There simply was no water in the radiator, but the temperature gauge had not moved, so there was no warning ! Anyway, there was water everywhere, and once we hooked up the garden hose from the tap in the front yard, it did not take long to establish water was coming from the radiator core quicker than you could put it in. So, what do we do next ? I don't subscribe to emergency road service, and the 'old' brain needed to function, and function in a hurry ! Luckily, I had my tools on board, and it did not take too long to remove the plastic cowling and fan and viscuous coupling. I was careful to leave the pulley in place that is attached to the water pump boss and drives the power steering pump - I really did not fancy driving the car without the power steering. It would take someone with stronger arms than myself to drive a 6.9 without power assistance.

I decided to head for home and the safety and convenience of my garage - there simply was no opportunity to effect a repair of any description and although there was no water in the cooling system I just had to take the chance. As good fortune would have it, home was only a couple of miles away, and I managed to drive and coast there (without engine running) and the car did not overheat, so I think I got away with it lightly - no overheating, according to the gauge, occurred at any time. Will keep you posted of progress. Regards Styria

 

[Michel]

Sorry to hear about your misfortune Godfather.

Very frustrating when that happens on a busy highway.

Any idea why the fan did what it did?

 

[Styria]

Hi Michel, I don't know at this stage as simply I have not completed my checking and examinations. I have removed the radiator core - damage pictured below in due course.

I have also removed removed the water pump as well as the housing that fits between pump and engine block. There was no way that I could make that pump budge from the housing. Tapping with hammer as best(and gently) as possible, and placing pressure between the gooseneck of the pump and the block produced zilch movement. So I removed the lot and even on the bench I had the dickens of a job to separate the two items. The problem ? Corrosion around the opening where the impeller is almost an interference fit. ...and the lower flanges of the housing, you might ask....certainly, Sir, further corrosion with subsequent repairs required. Loverly !! .....but no good chucking in the towel....Regards Styria

 

[BenzBoy]

Folks - remember my post a little time back about a low water alarm? The temp gauge in most cars will not read if the probe is NOT in water. Thus, a water loss will not register on the gauge. If you miss the gush of steam you may well overheat the motor before you know anything is wrong.
I am sorry to hear about your problems Styria and hopefully you caught it all before it caused real damage. Remember the old Irish Blessing? May all your troubles be little troubles.
Regards,
Benz-Boy

 

[TJ 450]

Sorry to hear about that, Styria.

I overheated my 500 SEC the other week. This occured after changing the coolant, where there was a large air pocket and the thermostat did not open. The temp gauge did not register until the coolant expanded, then all of a sudden, the gauge started moving when the thermostat opened (sender is after the thermostat). I pulled over in a hurry and cut the ignition and it just boiled over... a very frightening experience. It turns out there was only 5 litres of coolant in there.

There are no signs of blown head gaskets yet, but the engine was definitely placed under great stress and it is alloy.

Was there any coolant left in the system, Styria? No coolant means no reading on the gauge at all, if the gauge was still in the normal operating zone, I'm confident that you didn't overheat the engine.

Tim

 

[WGB]

Sorry to hear about your predicament.

Unfortunately most temperature gauges seem to need water in the engine to work and will not read hot when drained.

Those of us who have 126 type replacement header tanks will have the blank fitted to the side for fitment of the water level sensor.

Maybe we should be looking for the bits to put in it and using the spare bulb space in the instruments?

Bill

 

[BenzBoy]

So the 126 had a water level sensor and the current crop of M-Bs don't. I wonder if there is any reason?
Regards,
Benz-Boy

 

[Styria]

I can't accurately comment on whether or not the gauge registered without water in the system. All I know is that the gauge never registered overheating initially with all the water disappearing pretty smartly through all the holes in the radiator core. I know that there was water still in the system when I first pulled up with the noise coming from under the bonnet (the fan hitting the top tank and core).

Whilst stranded, but with the garden hose on hand and filling the system, or at least trying to, there would have been little, if no water in the system. After deciding to carry on to get home the last two miles (approx.) and coasting with engine shut off for 50% of the time, the gauge registered 100 degrees centigrade with no water in the system. Anyway as I said previously, I'd show some pictures. The first is of the radiator core, obviously beyond saving. A new unit has been ordered and it will have to come from Adelaide.



The water pump housing showed its normal corrosion problems on the bottom flanges..naturally, those surfaces should be dressed before the housing is refitted.


All I have now is a great big void where all the damaged parts have been removed from.


I have never particularly liked the task of removing that water pump housing, as I always seem to have difficulty keeping the three gaskets in place, and then having to refit that spacing washer between the housing flange and the Air Con bracket - a real cow of a job, but you've just got to do it. On the Astral Silver 6.9 that spacing washer was missing. BTW, completely out of the blue...why do we call washers "washers" - it really just doesn't make sense - I mean, what about the washer we use in the bathroom. Funny language that...English. Regards Styria

 

[s class]

I have the W126 header tank in the 280SE, and I have equipped it with the level sensor feeding a spare bulb in the dash cluster. It's already saved my engine once. I'm in the process of doing the same on the blue 6.9.

If you have the W126 tank (in itself not expensive), then the sensor, plus o-ring and circip all in is only about $20.

 

[-bb-]

Ohhh, sorry to hear about that. The thought of cooking a 6.9 is one you dont really want. As you know, I was worried about same late last year when mine overheated while doing laps around Oran Park.

One question: Why dont you have road service? It has come in handy several times in the last couple of years for me.

 

[Styria]

The fan is second in line to cause all this destruction. Whilst I still have not bothered to check things properly, it would appear that the water pump boss may have shifted, rendering the fan all wobbly - you have already seen a picture of the core, now it is the turn of the fan to become photogenic.




bb. - you ask why I am not in the NRMA Road Service - good question and I don't have a really good answer for it. So far, in about forty years, I've probably been stuck about four times - once I used the NRMA (at age 20 or thereabouts), three times I got myself towed, and the rest of the time I managed on my own accord - oh, twice I've run out of petrol, but got saved by Nos. 1 and 3 sons.

The last few years have witnessed a continual decline in quality and scope of the service offered by their Road Service. NRMA Insurance Ltd. is now a big player, a publicly listed company, and its aim is now focused on providing greater and increased benefits to shareholders. Nothing wrong with that - it's just a sign of the times. Of course, it should also be remembered that the NRMA is no longer associated with the Road Service. Two separate companies. I have other points of view as well, but these would only spoil the thread. Regards Styria

 

[Michel]

One question: Why dont you have road service? It has come in handy several times in the last couple of years for me.

Godfather having road service?

C'mon man....

This would be an insult....

 

[WGB]

So the 126 had a water level sensor and the current crop of M-Bs don't. I wonder if there is any reason?
Regards,
Benz-Boy

All my last Six Benzes including my two present ML's have water level sensors as far as I know BB.

I know my ML 500 has one because it went on one day with a cold motor and needed a 50 ml top up.

Bill

 

[BenzBoy]

All my last Six Benzes including my two present ML's have water level sensors as far as I know BB.

I know my ML 500 has one because it went on one day with a cold motor and needed a 50 ml top up.

Bill

Hmm. I hope this is so. I shall investigate. Neither the ML nor the CLK make any mention of it in the handbook.
Regards,
Benz-Boy

 

[Parks]

One question: Why dont you have road service? It has come in handy several times in the last couple of years for me.

To much of a tight ass!

 

[Styria]

Whilst I now know what damage has been caused, it is far from clear as to what the actual cause was.

In a nutshell - busted radiator core, fan blade AND viscuous coupling unit. Whatever it was, and we'll never know, some object fell between the radiator core and the ROUND part of the fan and got caught in that area, destroying the various bits and pieces. In fact, the force was such that it bent the viscuous coupling shaft and it is immensely strong and stubby. So, the force of damage must have been immense.

Water Pump - won't go into the details, suffice to say that it has now been rebuilt, and rebuilt with great difficulty. The pump, to the best of my memory, has been in Gleaming Beauty ever since I bought her, but the pump was reconditioned about ten to twelve years ago. and has therefore lasted very well - but I found some very strange items, the same as with the pump on the Astral Silver 6.9, that really do not seem original on 6.9s as I know them. Still shaking my head - odd seal and shaft, pump boss etc. etc. - what a hassle. Anyway, it's pretty well sorted now. Regards Styria

 

[Styria]

Well, Gleaming Beauty is on the road again - to be precise, for the last day and a half and I am pleased to report that all seems well now. Just harking back a little, there is no way I'll ever know what really caused all this mayhem under the bonnet. I have already referred to the bent shaft of the viscuous coupling unit, but additionally even the boss that attaches to the water pump shaft got twisted in the process. I had to have another boss modified and machined. I did have a spare unit, but it did not fit the shaft on my pump ! An absolute mystery.

One of the jobs I find quite trying is the refitting of the water pump housing - the casting that fits between pump and engine block. The difficulty relates to the positioning of the three gaskets, the large one in the middle and the two small ones for the bottom flanges. You've got to get them right, or else you'll have water leaks and this can mean starting all over again - and I have done that before today ! Anyway, I decided to coat the block and flange mating surfaces with Permatex aviation gasket maker prior to have a trial or 'in limbo' fit BEFORE fitting the gaskets. In other words, the whole assembly (with water pump attached to the housing as well) is secured by lugs or even screw drivers, and stands proud from the block at a distance of about two to three millimeters. This then gives you the chance to insert the three 'dry' gaskets and position them correctly. For the bottom ones, it pays to have a good lead light and a mirror to ensure that all items are in the correct location. As I said, you don't want to start all over again. So far, so good - no water, nor any other leaks at the moment.

The radiator core is new - $640.00 Viscuous coupling - reconditioned $280.00, Water Pump repaired and resealed, second hand fan $80.00 and my time. I am glad it's all done - you really know that you need to call it quits when spanners that you drop finish up in a location one meter away, and you have difficulty retrieving it, or you never seem to find the right spanner and where you have put it - and then you stand there thinking 'what am I looking for' ? It can be like that. Regards Styria

 

[SEL_69L]

I'm glad the repair is finished. I am also glad I wasn't driving at the time! I would not have had the tools on hand, and would have been forced to get NRMA road assistance to get the car removed. A very good thing the calamity did not happen far from home.

regards SEL 69L

 

[Michel]

Nice to know you're back on the road with GB Godfather

 

[Styria]

Nice to know you're back on the road with GB Godfather

Thanks Michel - so am I (glad that is), plus quite a few dollars poorer for the experience. As a matter of interest, and I would be interested in comments relating thereto, my radiator guy reckons that the only decent core one can buy nowadays has to come from Adelaide - apparently, everyone else's radiator cores are 'crap' and everyone seems to have gone out of business and/or items are now coming from China. Regards Styria