Largest 124 radiator.

[WDB124066]

Anybody ever fitted an SL M104 VC to their 124, P/N 103 200 06 22. Cuts in 4 Deg C cooler than the 124 o M104 one.

If it fits I may just do this.

Or even one off a W140 M104 car, would anybody care to make an educated guess at to weather they would fit a 124 Engine assembly...

 

[brucemillar]

This may be of no help at all. But, hey who knows worth a shot.

On my (now famous) V6 Pajero. I struggled for a long time with engine temp problems, such as:

Running to hot = 97c+
Running to cool = 75c

This was after I had blown a head gasket and replaced the water pump etc.


Using an infrared laser thermometer allowed me to see what was actually happening in the engine in real time. Like you I had no coolant loss.

What the thermometer showed up was a blocked rad half way down the core and on one side. This was throttling the flow through the system.

I had a re-core done for less than the cost of new. (Mine has a brass topped rad). I got them to fit larger diameter tubes n the re-core to improve flow and cooling.

Still had the same issues.

Dropping the engine temp sender in kettle of boiling water, showed that the temp gauge was over reading by up to 17c. Replaced gauge and repeated the test. Gauge now showed 100c at boiling point.

This still left the car running cool at times.


Replaced the stat with a genuine Mitsi part. With a marginal improvement.

I then discovered that my expansion tank cap was not sealing correctly, despite appearances. I found this by accident, when I stopped to get petrol and noticed the smallest wisp of steam at the grille. Made a new rubber gasket.

When the expansion tank was fixed I then was getting steam (no coolant) escaping at the brand new rad cap. Close inspection showed the lower rad cap seal was not seating correctly onto the rad neck before the expansion hole. Bought a genuine Mitsubishi Rad cap. Rather like a domestic tap seat. The top seal was fine it was the inner that was not sealing.

BINGO.

So it was two tiny undetectable leaks, both from sealed caps and a blocked core. The lesson for me was that the aftermarket parts that I had used were a complete waste of money.

The infrared thermometer is a great bit of kit. Allowing you to see true temps at any point you aim at. You can then follow the flow around the system.

Good luck.

 

[carat 3.6]

Anybody ever fitted an SL M104 VC to their 124, P/N 103 200 06 22. Cuts in 4 Deg C cooler than the 124 o M104 one.

If it fits I may just do this.

Or even one off a W140 M104 car, would anybody care to make an educated guess at to weather they would fit a 124 Engine assembly...

They both fit.

 

[grober]

I would echo the points above.
1. A decent IR thermometer is a useful bit of kit

2. Often "mystery" faults turn out to be down to simple understandable but erroneous assumptions. e.g. that new replacement parts are without fault- sadly with todays quality not always the case.

 

[Deadly Dave]

Is the engine undertray still in place ? If its missing it can affect airflow.

 

[WDB124066]

Yes under-tray is still there, they do get hard life but it is still there in all its fineness.

Here is a shot of the rad when they opened it up. And a shot of the debris that came out when we cleaned the rad and condenser a while back.

Bruce I hear precisely what you are saying and had something very similar with a Toyota just a few months back this is not the problem on the Benz - and everything [including all fluids] is a Genuine part on the car except for the battery, tyre valves, caps and balance weights. Hoses were replaced about 40 000 kms ago when we did the first HG job.

I think a temp survey is a good idea - may reveal something...?

I had thought that HG bits had got stuck in the heater core and after the rad was removed cleaned and refitted it was better until I hit the heater. Maybe bits are still in the system and have beme dislodged after I opened up the flow through the heater...?? Bit of a long shot really.

Anyway I think if I get the small panel damage fixed and the survey shows nothing concerning I will fit the lower kick in temp VC. Yes it is the same as the mod grober posted but I'll just go with an SL or W140 animal first. Saves a bit of mucking around.
One other thought was that in time the fan itself may suffer from efficiency drop, it may loose its twist of the blade or some such thing...? Other than that it may be a matter of just replacing the water pump to cover what grober was saying above, it may be new-ish but....???
Let's start with a survey, then a new lower temp VC, then the pump, then a bigger better rad in that order - yes?

 

[grober]

What was the make of the replacement pump? Did it have a plastic or metal impeller? Changing the pump on a M104 is fairly labour intensive and might put it on a par cost wise with a new radiator----making it a toss up between the two options. Thorough thermal survey first- one step at a time.

 

[WDB124066]

It was a Genuine one that the Dealership were selling at the time. I think it was a metal impeller. Somebody a while back commented that you can open them up and see inside without removal. How much you can see and whether you can check the fluid galleries properly that way is another thing I guess.

Will have to wait a while to get the survey done, I am away from my Mechs and their array of tools and things.

 

[WDB124066]

Where exactly should I be taking these measurements and under what conditions...?

1] Top and bottom of rad
2] Inlet and outlet hoses
3] Water pump.

 

[brucemillar]

Where exactly should I be taking these measurements and under what conditions...? 1] Top and bottom of rad 2] Inlet and outlet hoses 3] Water pump.

Check the rad top to bottom and side to side. Then I would try and follow the engine coolant flow. I was looking for temp differential between gauge and reality. So checking around the gauge sender, stat housing etc.

The thermometer I have allows you to hold the trigger as you scan an area. You can see hot or cold spots like this.

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[hotrodder]

As Bruce said. Bulk coolant flow through the rad is like



and you're just looking for hot or cold spots really. Temp drop across the rad should be somewhere in the ballpark of 15 - 20° once the engine is upto operating temp i'd have thought off the top of my head*. You've got a larger single row core so either i was remembering wrongly (more likely) or you have a 'better' core design than the mine had

I've just dug out the old water pump from mine (kept it as it only needs new bearings & seals, otherwise it's pretty much spotless inside)... can just make out the edge of the impeller through the 'stat housing and reach it with a small telescopic magnet

Unless i've missed it we still don't know how hot it gets in heavy traffic conditions? 107°C has been mentioned... is that it or do the fans struggle to keep it below 110°?
Obviously compared to many countries the UK rarely sees properly hot and humid ambient temps but FWIW when we do get a hot spell it still takes properly heavy Sarf London traffic for mine to nudge over 100° and the fans (bearing in mind one of the leccy fans is dead) keep it between high 90s and 110ish

Personally first thing i'd do is buy a new rad cap unless it was already replaced recently... they're dirt cheap, the pressure stages get tired with age without becoming noticable like tired seals and unless the header tank is over filled that won't necessarily result in coolant being puked, just vent too early preventing the system from fully pressurising. It's pressure that's mostly responsible for raising the boiling point of the coolant... 50% antifreeze boils at ~ 107°C at standard pressure, on the open road when the engine is at higher rpm the waterpump pressurises the coolant in the engine (pumping away while the 'stat restricts flow out of the engine). At idle (and obviously after switching off a hot engine) not so much hence allowing the system to pressurise. If any localised boiling occurs around the combustion chambers things can rapidly get worse as a vapour pocket forms...
Compared to water antifreeze is pants at removing waste heat (has about 1/2 the specific heat and 1/2 the thermal conductivity), i run around a 40% mix as the freezing point is still way lower than the UK needs and it's still 'strong' enough to inhibit corrosion as long as changes aren't neglected

If the rad/temp across the core checks out then once the fan shrouds/airflow into the engine bay is sorted i'd look at the fans again... if the viscous jobby is locking up properly then instead of replacing it with one that kicks in at a lower temp i'd change the leccy fan switch first 'cause it's cheaper/easier/faster. IIRC they're available with different temp ratings and/or can be tweaked by adding a resistor to make them kick in earlier with regards to coolant temps and/or refrigerant pressure?

It's only a guess but i wouldn't be surprised if, with at least some of the hot running m104s, corrosion of coolant passages is often to blame? Even with a one owner from new example that's been religously serviced because a stamped up history is no guarentee that the work was actually done... we've all heard too many stories about filters, spark plus and the like. Paying someone to change the coolant doesn't guarentee it's been done properly/completely and drained from block as well as from the rad

* as well as engine efficiency part of the reasoning behind higher 'stat temps is rad efficiency... don't want a massive temp drop across the core and ideally the average temp of the rad should be as high as practical because the larger the temp difference between the rad and ambient air the more efficiently the rad works

 

[WDB124066]

It will see 115 Deg C easily enough [and climbing] in summer at just about any light you choose. It relys on the electric fans to bring it down, the first being the over pressure fan. The VC is permanently engaged. It gets so bad that it will spit out refrigerant to the point where the over pressure fans won't come on at all because the AC system has dumped so much gas, the coolant system then gets much hotter and relys on the over temp fans at 107 to do their trick. Once they come in it will eventually drop till they switch off but only for a wee while before they are called upon again.

Before the HG job it always sat at 83 through 90 and the VC hardly ever came on let alone the fans etc.

It's the temp variation that is concerning me, it used to be very stable in traffic now it isn't. Introducing more airflow makes sense I guess, that's why I was wondering if a lower trigger point, stat & VC coupled with more efficient core may be what is needed to return it to stability - after the little bit of panel work is completed.

In the meantime I'll swap the caps over from the other car.
One thing I would like to check is the coverage of the new HG’s. Do they cover any holes in the block that the old ones never used to....??

 

[WDB124066]

Wonder if the pulley driving the fan is available 5 mm smaller...?

 

[hotrodder]

If the temp is climbing that high, that quickly, when stopping for traffic lights something has gotta be very wrong* somewhere? I can't see a bigger rad, more fan rpm, bigger/more fans making much of a difference (unless they're replacing knackered examples) and they're chasing symptoms rather than the cause; like you said the fans never used to cut in very often

Dunno what variations exist with different brands or ages of h/gaskets but AFAIK the only modifications to the origional design were to reinforce the known weak areas that aren't directly related to coolant passages, they were about external oil leaks? Most gaskets cover a bunch of coolant passages as they're used to meter coolant flow... large 'as cast' coolant passages in the block and head with small holes in the gasket to vent air etc and stop mosst of the coolant from taking a shortcut i.e. bulk flow wants to be from the pump to the back of the block, up into the head and then forwards

* I get it's been replaced but a dodgy waterpump kinda fits as to provide enough flow at idle they typically produce more than needed at higher rpm so a drop in pump efficiency for whatever reason can show up more in traffic than on the open road. Mine did that when its bearings died, steady 85ish all day long on open roads but catch a queue or set of lights and the temp would instantly begin to climb until the fans kicked in and instead of bringing it down they'd mostly just stabilise things at 110+ until traffic got got moving or i panicked and cranked the heater up
The only other thing that comes to mind (not very likely longshot) is someone going nuts with sealant and partially blocking stuff... at higher rpm coolant pressure overcomes the blockage?

 

[brucemillar]

Have you tried to get her to burp?

Get the front end up as high as you can -use ramps or a steep bank. Take of the rad cap. Start her up and leave her running for an hour or so. Any trapped air should be pushed out.

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[WDB124066]

Yes, fully burped Bruce - as far as we know.

HR you say you had those symptoms from a water pump only, nothing else changed? Temp survey should tell me if there is a prob with the pump I'm guessing.

As for Head Gaskets I know for a fact Daimler have struggled to control these locally.

It would be very interesting to see how much of what holes they cover! It's that kind of problem - especially as three others here have exactly the same symptoms after pretty much the same history.

 

[rorf]

You mention that before the head gasket job temps were between 80 and 90 - there's your problem!

Was the head skimmed, maybe compression ratio too high, maybe valve timing now out, maybe passages blocked with crud and gasket sealer, maybe wrong head gasket, maybe a water passage restricter has been left out.

Bigger radiators and more fans will not fix your problem; looks like head off again.

 

[hotrodder]

I'd have thought things like valve timing or compression ratio from skimming too much would have other effects beyond running hot when idling only? Partially blocked/gumed up water passages fit though

HR you say you had those symptoms from a water pump only, nothing else changed?

Only thermostat and coolant 'cause it'd be mad not to at the same time. Oh, and maybe the aux belt tensioner/some idlers
Bought the old barge with ~178k on it, hit properly massive delays driving it home down the M1 (the really annoying sort where traffic is constant stop/start crawling so can't just switch off and chill) and the viscous fan kept the thing cycling between mid-high nineties and just over 100° the entire time. Heater wasn't really on and it's fan was dead so wouldn't do much to lower temps anyway

About a year later the temp would start climbing pretty quickly when stopped at lights etc after leaving a motorway. This was accompanied by a small and (initially) tricky to spot coolant leak as the pump was weeping. By the time i got around to changing the pump the leak was a chunk worse and the car would mark it's territory when parked up with a steady drip from the pump pulley. You could charge up and down motorways at *cough* mph with it sitting at a steady 85ish °, it was only in stop/start traffic it struggled to stay cool and relied heavily on its fans

New pump and the running temp was waaaaay more stable in traffic. Couple of years after that the origional rad started weeping and with a new rad in it temps were even more stable... can't remember the last time the viscous fan has cut in, with the 20 - 22°C ambient temps we currently have 15 - 20mins of stop/start crawling along the A20 would get the temp upto maybe 95ish°

No doubt it's possible to get air locks (managing to fit the 'stat the wrong way so it's bleed hole isn't at the top?) but IME the m104 self bleeds really quickly as long as the heater is set to max... no bleed points to play with, just run the engine and top the coolant up as the level drops

Nicked a couple of pics from the internet and overlayed them to show how the gasket meters/restricts flow from the block to the head in most areas other than the back of the engine



Blockages/corrosion around the waterways circled in green would be bad as would enlarging the small vent holes to match the passages in the block and head

I can't see temp surveys telling much about the waterpump... if it's to blame it'll be something that messes with its efficiency like wobbly bearings, a mickey mouse impeller etc. 'Cause it's simpler/faster than pulling the head off again i'd probably slip the belt off to see if there's any play in the pump and if that checks out dump the coolant and have a poke around with a bore scope after removing the 'stat

 

[ivan1983]

On my W126 i think the pump was on its way out, a weird way I found to bring the climbing temp down was to take it out of D and in to 2 then hammer it to the red line. Think would bring the temp down to normal levels. Im guessing the higher RPM caused the pump to shift more water or the higher RPM caused more airflow from the fan or a combination of the two.

 

[brucemillar]

I'd have thought things like valve timing or compression ratio from skimming too much would have other effects beyond running hot when idling only? Partially blocked/gumed up water passages fit though Only thermostat and coolant 'cause it'd be mad not to at the same time. Oh, and maybe the aux belt tensioner/some idlers Bought the old barge with ~178k on it, hit properly massive delays driving it home down the M1 (the really annoying sort where traffic is constant stop/start crawling so can't just switch off and chill) and the viscous fan kept the thing cycling between mid-high nineties and just over 100° the entire time. Heater wasn't really on and it's fan was dead so wouldn't do much to lower temps anyway About a year later the temp would start climbing pretty quickly when stopped at lights etc after leaving a motorway. This was accompanied by a small and (initially) tricky to spot coolant leak as the pump was weeping. By the time i got around to changing the pump the leak was a chunk worse and the car would mark it's territory when parked up with a steady drip from the pump pulley. You could charge up and down motorways at *cough* mph with it sitting at a steady 85ish °, it was only in stop/start traffic it struggled to stay cool and relied heavily on its fans New pump and the running temp was waaaaay more stable in traffic. Couple of years after that the origional rad started weeping and with a new rad in it temps were even more stable... can't remember the last time the viscous fan has cut in, with the 20 - 22°C ambient temps we currently have 15 - 20mins of stop/start crawling along the A20 would get the temp upto maybe 95ish° No doubt it's possible to get air locks (managing to fit the 'stat the wrong way so it's bleed hole isn't at the top?) but IME the m104 self bleeds really quickly as long as the heater is set to max... no bleed points to play with, just run the engine and top the coolant up as the level drops Nicked a couple of pics from the internet and overlayed them to show how the gasket meters/restricts flow from the block to the head in most areas other than the back of the engine Blockages/corrosion around the waterways circled in green would be bad as would enlarging the small vent holes to match the passages in the block and head I can't see temp surveys telling much about the waterpump... if it's to blame it'll be something that messes with its efficiency like wobbly bearings, a mickey mouse impeller etc. 'Cause it's simpler/faster than pulling the head off again i'd probably slip the belt off to see if there's any play in the pump and if that checks out dump the coolant and have a poke around with a bore scope after removing the 'stat

Great info here. Thank you. I think a temp survey will help rule things in or out. Agreed if it is the pump this may not help. Can you see if you have good circulation at the top of the rad? On my Pajero I have a very obvious coolant flow from right to left at the rad top.

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