Re: Finding coolant leak and checking temp gauge - Page 3 - PeachParts Mercedes-Benz Forum

meltedpanda · #31 12-26-2006, 05:23 PM

I have asked this as well, a few times, ARE YOU GETTING HEAT?
does it respond to temp gauge input?
If so Mike is right, it does not sound like a water pump

michaeld · #32 12-26-2006, 06:26 PM

Is there a consensus that the MBz Technical Companion is wrong on page 114 when it states that one can test the water pump by feeling the outlet hose to the radiator?

Miked and Meltedpanda,

Ah, now we're really getting somewhere! A positive test of the water pump!

You are saying if my heater works, coolant IS circulating through the system via the water pump and moving into the heater core to heat the interior. That if the heater did not work, this would indicate that the water pump was not working. I have NOT disconnected my heater core, and as of the last time I used it, my heater seemed to work fine (I haven't used it since my leak problem). I will go ahead and try it again, but I believe that I will have heat. Also, I ran the car for 40 minutes (since the leak problem) on one occasion and 15 minutes on another. Neither time did I "get hot enough to peel the paint" (in fact, I had the pressure cap off and was inserting a thermocouple in the expansion tank during the 40 min idle, and the car never got above 180F when giving the car some gas).

The reason it is important to me to verify my water pump is because I am about to drain the coolant and do the following work:
1) bypass the servo (which, when I opened the hood, was hissing and sputtering coolant; also, there was a pool of coolant located in that area). Since my heater core is almost definitely not the culprit, I can only surmise the servo is even though I haven't been able to get it to fail again by idling.

2) I will install a different water temp gauge (after verifying it in hot water) so that I can verify whether I even am overheating or not.

3) I will remove the upper housing and install the new gasket to try to deal w/ the water pump housing leak.

If I had sufficient reason to believe that my water pump had actually failed, or was failing, I would simply pull the sucker and work on installing a new one. Since I have to pull the distributor in order to do the job (according to the manual) I don't want to have to do it unless the unit is actually failing.

Now, Miked mentioned that deposits can essentially rob the water pump of its functionality even if the unit itself is pumping. I'm a little bit concerned about that also. When I first got the car, it seemed to run a little hot after a long drive. I discovered that the radiator was about 40% blocked and had the core replaced. A few months ago, I had the system professionally backflushed. But even now, I am seeing particles of gunk in my coolant (the coolant itself is nice and green, not milky at all). I'm wondering how "clean and open" the water passages are in the engine.

milterino · #33 12-26-2006, 10:42 PM

I checked my 1976 water hoses for pulsations , top and bottom, and could not feel anything that would indicate whether there was or was not a water pump working. Milt.

michaeld · #34 12-27-2006, 12:40 AM

Milterino,

THANK YOU!!! No matter who said the MBz Tech Companion's "pulse test" would not indicate a water pump's performance, there was that little gnawing of doubt until someone with a healthy cooling system told me that they had actually tried it. I needed to hear that.

Miked was right and the Tech Companion was wrong. I appreciate having you guys to talk me through the theory and practice of keeping these cars running.

I will post back in a couple-few days to let y'all know how things are going.

I hope these repairs do the trick and my heating issues are behind me.

Mike D · #35 12-27-2006, 08:27 AM

It does not mean I was right and the manual was wrong. It means that we as un-trained MB repairmen can not feel the pulsations or they do not register.

I can listen to an in-line Cummins engine and tell you which exhaust valve is leaking on what cylinder. I was trained by Cummins to diagnose THAT particular sound. The owner of the truck can't diagnose it. I'll be damned if I can hear that," kerrsnickety whack whack" sound my wife tells me about just before the power steering pulley goes sailing across the yard.

michaeld · #36 12-27-2006, 04:32 PM

Quote:

Originally Posted by Mike D

I can listen to an in-line Cummins engine and tell you which exhaust valve is leaking on what cylinder. I was trained by Cummins to diagnose THAT particular sound. The owner of the truck can't diagnose it. I'll be damned if I can hear that," kerrsnickety whack whack" sound my wife tells me about just before the power steering pulley goes sailing across the yard.

I about laughed my rear end off after reading that last line. That final sentence is a classic line!

One my w116 forum, one of the savvier fellows noted that after 15 min of idling, I noted that my top hose was hot, but my BOTTOM hose was still cool. He believes that indicates a flow issue with the radiator. I had my radiator recored just over a year ago, but maybe that's my problem?

I will soon be finding out whether I'm running hot, as I'm going to install a different gauge (after testing it in hot-boiling water as a complete system for accuracy).

juribe2 · #37 01-04-2007, 07:01 AM

Hi,

Have you found the leak source? How did the tests go?

michaeld · #38 01-04-2007, 07:23 AM

juribe2,
Hey, thanks for remembering my situation. I appreciate that.

I've had some frustratingly slow progress, mainly on just getting an idea of what parts to order and waiting for the parts.

I have removed my servo, and will essentially simply bypass it for the time being. I believe THAT is what leaked (exploded would be a better term), and am acting on that premise. I toyed with the idea of installing a valve - as many have - but am somewhat confused as to where to install it; so I'm just moving on for now.

I found a couple of leaks in the water pump, you might recall. One was in the upper housing, and one was in the 42mm bypass hose that connects between the head and the water pump; the other was in the upper housing.

I had a hard time getting my hands on that 42mm hose, as MBz sells it for $100/meter and I needed like 2". Finally got it. Then, as I was looking at the upper housing, it appears - for some reason I can't understand - to be rather badly pitted ON THE OUTSIDE where the hoses connect, and now I'm thinking I ought to replace it as well. So far, I've only been able to find it thru a dealer, and they will ship one to me - for $100. (I think MBz thinks I'm made of $100 bills).

I also wanted to install a second temperature gauge - that came w/ wiring, gauge, and sending unit - in order to simply make sure what temp the car is actually running at. I had all kinds of trouble (mostly due to my own ignorance) of finding a gauge. BTW, the 4.5L M117 has an M14 thread with a 1.50 pitch for its temperature sending unit. I ordered a Sunpro CP8201 with a CP7573 metric adapter kit, but am still waiting for it to arrive.

My plan is get that water pump leak taken care of, bypass the servo, install the new gauge (just on the firewall for now), and then see how I'm doing.

Of the elders on my other forum - w116.org - says he believes I've got a clog in my radiator, and suggests I take the radiator out of the car and have it professionally flushed. If I'm running hot on the gauge when I get it all back together again, I will do that. If I'm still running hot, I'm going to take the car to MoterWerks and have them diagnose my problem.

I was thinking of posting back to the thread and giving an update, but really don't feel like I've got much of an update to report. But I really appreciate your thoughts.
Mike

Mike D · #39 01-04-2007, 07:59 AM

Actually, the upper hose being hot and the lower one cool is an indication of your radiator doing it's job. If you use an infra-red thermometer on your radiator you will find the temperature decreases as you pan down the radiator fins. Since you had the radiator re-cored a year ago I doubt you have any blockage. You can always check it by pulling the lower hose and running water through the radiator. With the thermostat installed you should have more water flowing from the radiator outlet than the lower hose.

The pitting on the hose connections is pretty common. It's usually caused by an incorrect mix of water/coolant or extremely alkaline water (which I believe you guys have in Palm Springs). All you purists may want to look away for this next bit. I have fixed this by soaking the housings in a weak acid solution (vinegar works pretty good), cleaning the housing with a brass bristled brush and applying a thin coating of (gasp!) JB weld. You want to avoid getting the JB weld on the inside of the housing because the constant temperature changes combined with immersion can make it flake off if it is not perfectly adhered. Give the epoxy at LEAST 2 days to cure. File and sand until smooth and you're good to go.

juribe2 · #40 01-04-2007, 08:43 AM

I'm cheap too. That upper housing fixing procedure sounds ok to me.

If good quality tap water isn't available, I would buy a couple of water gallons at the supermarket and use those to make the 50% coolant/water mixture.

I'm with Mike D about your radiator. Is too soon to be blocked.

I hope you get your car fixed soon. Please keep posting and let us know any updates.

michaeld · #41 01-04-2007, 01:21 PM

Mike d and Juribe2,

Thanks for the info on the upper v. lower hose. Always glad to hear that what my system is doing is what it's supposed to do (particularly when I'm fearing "issues"). I too was somewhat surprised that I might need to flush a new core so soon. The day I noted the difference in hose temperatures, I had let the car idle for 15 minutes. The top hose was noticeably hotter than the lower, and I added that detail in th event that it was relevant.

The water in the Palm Springs area is mainly well water. It is delicious (my local water has won worldwide recognition), but it is also very high in minerals and deposits. I have use distilled water since I've owned the car, but then there's that 28 years of ownership that came before my year.

Thanks also for the note on good old J-B. I was wondering if I should use RTV silicone or JB, and found a couple of articles detailing success with the use of J-B Weld on pitted engine metals. It's good to hear someone independently ratify a plan. I would buy a quality used or discounted new housing, but there's no way I'm going to fork over a Franklin for one.

I also appreciate the "how to" on application. I have only used the stuff a couple of times.

I most definitely will keep you all posted as to my progress. I'm not a mechanic, so the best way I can "give back" to the forum is by posting my experiences so others can learn from them.

I intend to write a "How to" on my servo removal/bypass, and on my water temp gauge selection and installation when I get everything back together.
Mike

hugtug · #42 08-08-2009, 05:30 PM

This is an old post but I was looking over it for water pump information.

I saw that some people are talking about using tap water. I would avoid it like the plague, no matter what tap it comes from

Distilled water is fairly available in many stores if you look. Either automotive stores or even grocery stores. Distilled water is lacking minerals (nearly 0%) and when you put it in your engine with coolant, it helps remove and keep deposits out. Since distilled water is lacking minerals, it naturally looks to latch on to minerals and dissolve them, which is what you want.

That's why it's not good to drink, since it steals minerals from your body - but this is a good thing when your CAR drinks it. Mineral heavy water, the opposite, from any tap, is what you don't want. All tap water, no matter what tap you get it from - will have plenty minerals in it. Don' use tap water, it is not worth it!

In fact I suspect the only reason there are deposits in the engine, is from all the previous owners who used tap water. After all, the minerals had to come from somewhere. The fact that older cars have these problems may be due to older mechanics and previous owners not knowing about distilled water back then in the 70's, and 80's. I thought by 2010 at least everyone would know about distilled water...