losing coolant, about 500ml for every 1000 miles.
Jacked the GL up, found coolant dripping from dirver-side. The lower portion of driverside radiator is wet. and above that there are some dried coolant dusts as shown in photo.
haven't checked the water pump yet, might need to remove the fan assembly to check water pump area.
seems the radiator is leaking.
Is this a rare case? since there are not many posts on this topic in this forum.
Thanks,


driverside radiator, around the coolant drain plug



driverside radiator, possible dried coolant

 

Not impossible at all for the radiator be leaking at the stage, it is less likely that it’s a water pump leak that is making its way forward given that the fans will blow fluids backwards and gravity will cause them to seep downwards.
Back and down. So look for leaks forward and up from where you see the water pooling.

 

The power steering heat exchanger, in this case exchanging heat into the power steering fluid, is inside the driver side tank. Your radiator is leaking from the o-ring where the power steering return line penetrates the driver side tank. Try tightening the nut you see there. They are known to loosen, probably due to thermal cycling. If I recall correctly it is a 18mm nut; you need a stubby wrench for clearance. If I had to do-over the radiator, I would, in addition to polishing the inlets and outlets, and silicone greasing the drain petcock, put Loctite on the threads of the tank penetrations. But they are not too difficult to re-tighten.

There is a very long o-ring between the tanks and the fins module. I do not know how vulnerable that is. It is thin, but thoroughly clamped in place.

Kudos to you for seeking out the actual source of leakage. You might get better results by doing so while the cooling system is hot and pressurized, but needless to say that is physically more challenging.

From all accounts, the water pump is as long lived as the engine internals. I recall maybe one or two instances of its replacement. The water pump is located on the opposite side of the motor from the power steering heat exchanger.

 

Thanks a lot for the advices. just ordered Genuine Mercedes radiator for $309 at FCPeuro.
once receiving it will try apply blue locktite to the power steering return nut threads.
Yes I tried to torque the nut, but it was hard to reach. will remove the fan assembly to have more clearance to tighten it, and also to check the water pump.

 

Well, to each his own, but if I was to tighten the nut, I'd wait to see if that fixed the problem before shelling out $300 for the radiator. Keep in mind changing the radiator is no small job.

I was able to tighten the nut with just a small crescent wrench. You can get a set of stubby flex head wrenches for under $20 on Amazon.

 

Late to the thread - has the top radiator mount been looked at for cracking? This is a common problem on 166, not sure if it affects 164.

On a 17 year old car I would not hesitate for 30 seconds to replace the radiator, good decision.

 

thanks a lot for the suggestions. will need to remove some parts to further check the top of radiator and the water pump area.
Luckily FCP euro has 90 day return policy. in case those parts are not needed.

 

Have not heard of any top mount cracking

Counterpoint: If it ain't broke, don't fix it. Whenever you disrupt a stable equilibrium, there is risk of destabilizing other items. It is not a small job, and if coolant has been properly maintained, there is little reason to believe either aluminum or plastic have degraded. The o-rings, yes, but they are held in place.

 

When you remove the fan, consider shaving off the bottom corners of the fan shroud. It makes reinstallation and later removal easier.

 

if the radiator is 16 years old and leaking, just replace it. It takes an hour for anyone competent to do it. Don’t go torquing old plastic before your new parts are there. No need for Loctite, just appropriate parts. If your coolant channels or heater core have never been flushed, now is the time.

 

yes it was a struggle to remove / install the fan.

 

yes no complains if the radiator and/or water pump is due for replacement after 17 years of usage.

 

This discussion reminds me of the one my mother-in-law had with her doctor about how to treat her breast cancer:

"Are you a 'throw away the apple;' or a 'cut out the bad part' person?" Neither way is "wrong" or "right" and both have their benefits and drawbacks.

 

Why don't you ask a MB dealership what the standard hours of labor are for the job?

 

Like I said, trim the bottom corners off the fan shroud and you will find it quite a bit easier. It lacks only about a half inch to clear the hoses.

 

My rationale would be to not disturb a stable situation if the repair is not urgent. I changed my power steering pump and then had to fix a coolant leak that wasn't there before.

It would be good to have the spare radiator on hand in case you break the o-ring tightening the power steering thingy nut.

The other thing that makes me hold off from non urgent repairs: Suppose I do the repair, and then wreck the car on the test drive afterward.

 

These 164s are getting long in the tooth, and have arrived the throw-parts-at-it stage.

If I owned one of these, and there was a problem like a leaking something-or-other, I would replace the leaking part and be willing and ready to replace other parts if needed. Collateral damage or domino-effect maintenance.

If committed to long term ownership on these things, expense cannot be spared. Otherwise the maintenance and repair snowball accelerates downhill and these cars start eating wallets exponentially.

 

There is no easy answer. Certainly, with Airmatic and the primary electrical system one is well advised to spare no expense and keep a close eye on the system status, as slow failure of one part degrades the others.

If it were an aircraft, the whole engine would be rebuilt on a schedule designed to eliminate virtually all in-flight failures. But this is not an aircraft. Component failure leads to you pulling off to the side of the road and calling AAA, not desperately hoping for a safe place to land.

If I could re-do my radiator replacement, I first would have been more diligent about finding the source of the leaks (it turned out it was power steering fluid and coolant leaking from a lower radiator hose). If I went ahead with the radiator replacement, I would have changed the power steering pump and reservoir, and low pressure hoses, and the upper and lower radiator hoses, and lower heater hose while I was in there.

There are two risks in doing any work. One is disrupting a stable situation; for example, if you change the thermostat, you may find the upper radiator hose o-ring cannot be reused. It was sealing fine; now it does not anymore. The other is installing imperfect parts; I removed a probably good radiator and replaced with one on which the drain petcock promptly failed and the inlet pipe had to be polished to make a good seal. A friend of mine laboriously installed a fuel pump only to find out much later that the one he installed was bad. It is no longer a world in which parts quality can be relied upon.

If you are willing to have a risky vehicle, change parts on an as-needed basis. This is cheaper but costs you in gray hairs. If you want as-new aircraft level reliability, do complete rebuilds of subunits, but understand this will be expensive (cost you will not recover if a rock falls from the sky) and still may cost you gray hairs.

 

Agree. On the other extreme is the impressive W212 10-year rebuild project @S-Prihadi is currently engaged with.

Data points on the maintenance spectrum:

- deferred maintenance --> not recommended
- fix only what's broke --> seems to be eric_in_sd's preference?
- preemptive maintenance --> this is my preference - fix what might be broke or could become broke, plus anything else in the neighborhood
- 10-year rebuild --> S-Prihadi example
- aircraft maintenance

 

Either way, you're spending the money. It's just a matter of when. I work on a case by case basis. If it will involve repetitive work down the line and something that's reasonably likely to fail, I'll replace it. But I'm not going to replace expensive parts that are working because they might fail - why certainly pay for something you may never need to pay for? Life is a gamble.

 

i’ll respectfully disagree with that sentiment and offer up my more pragmatic take… If it isn’t necessary, just disable it or retire it in place. For example, secondary air injection. Intake tumble flaps. Just leave it all alone and turn off the lights in the alleyway of the power plant that you don’t need.

And then systems that have the potential of prematurely ending the power plants life, such as cooling and lubrication, yes, sure fix that if it’s about to be broken - but only to the bare minimum necessary of ensuring continued operation.

It’s still just a $5000 car no matter how many parts you throw at it.

 

Trust me, I would love to retire unneeded components, such as the downstream oxy sensors and secondary air pump! Wanna fly to Idaho with your computer?!?

I just spent some time troubleshooting the secondary air pump. It turned out to be a disconnected vacuum hose on one of the valves. Aargh. Useless! All because the Los Angeles basin traps air.

 

Not the best policy for a vehicle, you should "fix/replace" the parts at about 90% wear. Especially suspension components.

But most of us are lazy, so we fix it when it starts to make a noise lol

 

Well, there's only a few things that you can tell are 90% worn While I generally take preemptive action, there have been times doing so has caused (or at least was closely followed by) a cascade of issues/failures.

 

Why spend $6000 to fix a $5000 car sounds like a poignant question. But it often not the relevant question.
If you enjoy your vehicle and like what it offers, the real question is $6000 versus $30000 - $65000 for a newer/new one to replace it.
Sure, you could replace it with another one of a similar age for $5000 (though not where I live), but the odds are pretty good you'll still be facing material repair bills in short order.
If driving what you have is still enjoyable it's probably worth the repair. But if you begin to look at it with distrust or distain, then that $5000 value becomes a whole lot more relevant.