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Climate control system crisis

Started by michaeld, 10 December 2006, 02:55 AM

michaeld

Update:
I cussed off the air inlet grille and am pretty sure I saw the passenger side of the firewall by taking off the panel below the glove box.  I didn't go any further tonight.  I saw no sign of any leak being present anywhere in the passenger area.

If anyone has ever had a heater core spectacularly fail (i.e. develop a big leak), where did they see the evidence of the leak?  I don't want to take any more of the dash apart than I have to to locate something that most likely isn't there (i.e. a leak from the heater core).  I'm trying to verify that there ISN'T one, rather than find one I strongly suspect is there.  I am 98% sure that my leak came from the ACC servo (even though I can't see any external evidence there, either - at least since I cleaned up the coolant).

If I CAN'T locate a leak in the heater system, I will be bypassing the servo (as per JCCP's documentary), installing a different water temp gauge, and driving the car around until I see either a) a leak or b) a hot gauge.  If I spring a leak, hopefully I'll at least be able to verify its location; If I'm still running hot (on the new gauge), it's to the mechanic for a full diagnostic. 

michaeld

Great googley moogley!

I was just looking at the engine trying to figure out where juribe2's mechanic put his plug to bypass the heater core, and suddenly I saw something clearly pertinent to my problem.

I had stuck a UV dye in the system to better find the leak, and ran the car primarily looking at the servo area.  The UV dye has a "glow" even w/o the UV light and glasses.  Well, tonight I just glanced at the water pump, and BLAMMO!  I spotted a leak coming from the joint between the pump itself and the upper housing (where the upper hose connects).  I had NEVER seen it leak there before, and believe me I have looked a bunch!  Maybe I needed the dye in the coolant to see?  Anyway, I tightened the bolts up, and will clean up the leak and run the car to see if I get any more coolant there.

Pumps will leak before they fail, but would they leak there (at the joint where the pump and housing connect)? 

Here's a pic:



The leak only seems to be occurring at the pump/upper housing (where the 212F switch bolts in) connection, and then dripped its way elsewhere.  Is THIS the divine sign that my pump has failed? I'd always thought pumps leaked at the impeller when they failed.

jjccp

Great googley moogley? You're not a Frank Zappa fan, are you?

Sounds like you are on to something. We're all getting an education here. If you don't see any leaking under the glove box area, I'd say your heater core is not the problem.

While you are poking around in the engine bay, make sure all those hose clamps are tight at the servo and also the lines to the heater core and any other coolant lines. You might have more than one leak.

Hopefully you won't have to touch the servo now that you found the water pump leak, but if you do, here's the size of pipe you need to make the splice. I said it was 3/4 inch before, it's actually 1/2 inch.

1977 280 SE
1978 San Juan 23
1979 6.9 #6846

Papalangi

I've only had water pumps fail at the shaft seal and those were on domestic cars.

The heater core failed in my '87 5.0 Mustang.

My first clue?

Near instant and total fogging of the windshield. :o

That and the stink of antifreeze.

The inlet and outlet piping were fine, it blew a seam if I remember rightly.  Took two days to take the dashboard out and replace.

Michael
'83 300SD, I'm back!  It's the son's new car (12/2020)
1976 450SEL, 116.033  Sold it to buy a '97 Crown Vic.  Made sense at the time.
1971 250C, 114.023
1976 280C
1970 250/8

jjccp

If anyone does need their servo repaired, I have to give my highest remommendation to Doug in Montreal, Canada that did mine.

I posted his contact info here:

http://forum.w116.org/index.php/topic,981.0.html

Jim
1977 280 SE
1978 San Juan 23
1979 6.9 #6846

116.025

Michaeld, *IF* memory serves from when dad and I replaced the water pump on my mom's 450SEL several years ago, that's the joint between the thermostat housing and the water pump where you see the UV dye, and there's a gasket that sits between the t-stat housing and the water pump.  Maybe it's not seated correctly or the gasket is leaking?  Just a thought.

michaeld

I understand, Styria.  When I come across a long post - and it aint dealing with a problem I've either got or worry that I'll get - I tend to "blah blah blah" my way through most of it.  But when it's a thread dealing with my trouble, I focus like a laser.

So far in this thread, I've learned how to spot trouble in a heater core, and that I don't have that problem.  I've learned how servos tend to fail, and that it most likely is my problem.  I've learned how to bypass a problematic servo, with excellent pictures to help me through the challenge.  I've learned more about how to test a sending unit, and what equipment will be most helpful to have.  Quite a bit, actually.  I can see someone in the future reading this thread and thanking God that JJCCP took some of the pics that he took.

I also now know a reputable guy to do my servo rebuild, if I decide to go that route, thanks (also) to JJCCP.  A prince of the realm, that JJCCP is.

But now there's a new tidbit of knowledge.  116.025 says that there's a gasket where my water pump leak is occurring.  It occurred to me that when I purchased my thermostat, I also purchased a gasket, believing that it fit at that housing.  When I got the housing off, it clearly was not right for my lower housing (where the thermostat mounts).  I thought that I had received the wrong part.  Now I have good reason to think that that gasket may soon come in very, very handy.  I'm pretty sure that I didn't throw it away, as i figured it would eventually (somehow) come in handy.  Now I'll search high and low for it, 116.025.  Thanks for that tip.

In any event,

michaeld

Styria,

No feeling of paranoia from me (even though I'm sure they ARE after me!).  I assumed the sheer length of the thread kept people from wanting to bother to read through that many posts in order to keep track.  That's why I started a new thread on a related but different topic.

Now, your question has been mine also: Are my servo leak and my hot gauge related?  I had been repeatedly told that I was NOT running hot, and that I must have a bad gauge.  I had made a few long drives, but the paranoia induced by the hot gauge had prompted me to pull off mid-way and have lunch in such a manner that the car could cool some.  The day I "sprung a leak" was the first day I decided to just drive straight in.  It's possible that I was never running hot, and that the servo leak was just a coincidence.  It is also quite possible (at least in my mind) that I was running hot, and that the servo failed because the water temp and pressure was too high.

It IS winter here, but I live in the S. California desert, so my winters are not particularly cold (70s-80s F).  The nights can be quite cold, but the car is invariably tucked away in the garage by then.

The water pump is about five years old, and has about 10,000 miles on it.  It is MBz; I can see the 3-point star near the 212F switch.  The original owner - a medical doctor - didn't seem to jack around with cheap parts.  I'd be surprised if anything on the car were aftermarket (except my radiator core, read below).

I had the radiator re-cored about 15 months and 6,000 miles ago.  I was told the rad was about 40% blocked.  The car temp was great until it all of a sudden showed hot on the gauge one night about 8-9 mos after the recore.

As I said in one of my last posts, I ran the car for about 15 minutes plus to further check for leaks and try to feel pressure from the hoses.  I noted the top hose got hot, but the bottom hose did not, during that time.  Is it possible that my recore needs a recore?  I'd like to hear more about that, as its still under warranty.  Two mechanics at that radiator shop told me I WASN'T overheating (the others being at the shop that backflushed my system, and a personal friend who retired after a career owning a transmission repair shop).

My plan is to go ahead and drain the system, bypass the servo, install a water temp gauge (after checking the system in boiling water for accuracy), and install a new upper housing gasket on the water pump.  Hopefully, that will take care of any leaks, and then I'll know for sure whether I'm overheating or not.  If I'm overheating, I won't mess around any longer.  I will either replace a component or two that I believe could be causing an overheat during freeway conditions, or I will simply take the car to a German mechanic and get a full diagnostic on the cooling system rather than continue playing with fire.  If I find that I had a bad gauge all along (and the servo just found its time to die), I will happily work toward restoring my ACC system.

jjccp

1977 280 SE
1978 San Juan 23
1979 6.9 #6846

michaeld

#39
Hi all,

Styria,

Have to ask a follow-up: do you believe that the radiator simply needs a good flush, or what sort of service do you mean?  The core I put in was brand new when installed (a whole 6,000 miles ago).  It is still under warranty, but I believe said warranty involved parts, but not labor.

JJCCP,
Thanks for looking out there.

I'm not ready to buy a servo yet.  To be honest with you, I still really don't know if the one I just yanked out is BAD for sure (I didn't test it, just pulled it; and when I had it out and looked at it, I couldn't see any sign that it EVER leaked!).

I've got a question for you, one for which a picture would do nicely.



You might notice I have the 4 separate hoses labed: it would seem that A connects to B, and C connects to D.  In any event, hose D, which came from the underside of the heating pump (at least I THINK that's what it is; I'm referring to the smaller unit that connects with 2" hoses to the side of the servo) points naturally wants to point straight up.  Was this the way it was for you when you disconnected your servo? 

In order to simply use your two short lengths of pipe, did you simply twist that hose (Hose D) up so it would connect to hose C?  I'm asking because I don't want to do anything to "anger the beast": when you have a lot of hot water going through a hose, you don't want it to encounter some strange new flaw that you incurred torquing a hose around!  The hoses seem pretty pliable, but I am afraid that bending it around might cause it to kink and restrict flow.

I might mention that I have also found difficulty on the "install new water pump gauge" front.  I purchased a unit that had several attachments for various sized sending unit threads.  Well, it turns out that the 450SEL had a TINY thread compared to other cars.  Too small for two kits to work.

So now I'm looking for a water gauge kit that will bolt in.  I am NOT going to drill a hole in my head (or my engine's either)!!!
Mike




jjccp

#40
Mike,

Your picture brings back fond memories for me from a couple of weeks ago. Now I wish I that I would have taken better pictures for you. Explaining some of this stuff with words can be difficult. If I knew how to mark up my pictures on the computer that would also help.

But if you look at this pic, you should be able to duplicate my efforts. I found it helpful to put the larger versions of your picture up side by side next to my picture on my computer screen.



The hose end that you have labeled as 'D' is where it all starts. That's where the coolant first comes out of the engine and goes into the little auxiliary pump, which you have now removed. 'D' is where the first splice (copper pipe for me) goes. You have to take some of the other little hoses and move them around (per my pic) so that everything lines up. There is enough play in hose 'D' so that you can loop it up to make the splice to 'A'. The first splice goes to the kinda of "Z" or "S" shaped little hose (it looks like you have it labeled as 'A,' you will have to rotate it up from where is normally goes). 'A' goes into the heater core inlet, which is the one that goes over to the driver's side of the engine bay and into the firewall. Next you come out of the other side of the heater core (passenger side of the engine bay, coming out of the firewall, the other end of your 'B') and plumb it into the only remaining hose, which sends the coolant back to the engine via your 'C'. Refer to the "coolant flow diagram."



Basically, 'D' splices to 'A' then 'B' splices to 'C'. That white thing next to 'A' in your pic is making it hard to see.  If you did 'D' to 'C' as you thought, you would be going out of the engine and then right back in to the engine and you would eliminate the heater core. 'D' is out of the engine and 'C' is back in to the engine. 'A is in to the heater core and 'B' is out of the heater core.

There might be one little hose left over that you don't need to use for the by-pass. But I can't really remember for sure.

Also, I found it easier to remove the bracket, which holds the aux. pump and servo, and remove everything as one unit. There is only one nut holding it on and it slides in and out of a tab type thing. Since you are already done with that step, you will probably want to take off the bracket now and reassemble everything as one unit before reinstalling it later on.

If the above instructions were not clear, I would be willing to walk you through the process over the phone. Send me a PM if you need more help.

Sorry, I can't help with the sending unit part, but I'm sure someone else will.

Jim
1977 280 SE
1978 San Juan 23
1979 6.9 #6846

michaeld

#41
JJCCP,
Boy, am I glad I posted that pic and labeled the hoses.  I almost didn't; I was so sure of how the hoses were supposed to route!  That part of my question was mere formality; my REAL question was whether it was okay to twist that "D" hose.

I understand your description: A->D, B->C, i.e. I can route it as you describe.  In fact, I now see that in your pics, you have the hoses that I have labeled D and B crossed, whereas I did not cross them.

I think I conceptually misunderstood what we were doing.

I referred to your heating water circuit diagram from the MBz manual, and traced the hoses: Hose "D" (as per my labeling) is the feed hose ("a" on that diagram) that begins on the driver's side engine and terminates at the heating water pump. 

Hose "B" (my label) is the return hose ("b" on the diagram) that connected to the passenger fender side of the car on the firewall/back side of the servo.

Now - "c" on the MBz diagram - the heater core, has a feed side (the passenger side) and a return side (the driver side) [US models]. 

What I conceptually attempted to do - and completely succeeded, I believe - was to route the return hose from the engine to the return side of the heater, and the feed side from the engine to the feed side of the heater.  I did not realize that I was supposed to cross those hoses.

In other words, to put it in kid's cartoon-drawing terms, I routed the hoses as though the servo were simply not in the diagram, and instead the hose paths were drawn in as they would have appeared to go had the servo not interrupted them.

From my point of view at the time, it was rather like the "Guinness Beer" commercials in which the mustachioed cartoon-figures say "Brilliant!!!" to each other.  I should have realized that they were always about to do something idiotic in the commercials!

As I said, I will re-route the hoses to match your description.

And, given your assurances, and the fact that my hoses seem to be in good shape, I will figure that that hose "D" will easily handle the gentle twist I will have to put it through.

Thanks again, JJCCP.  I clearly need a babysitter on this job!

On the "water temp gauge," I've got my eye on one that I think might work.  If it does work, I'll post the make/model #.

Styria,
Here's my plan, based on your recommend: I will get everything connected, and install the new water gauge.  If I'm running hot with the servo bypassed on the new gauge, I will go ahead and remove the rad and have it serviced prior to taking the car to the mechanic for diagnostic (for overheating).  If I'm not overheating, I will probably go ahead and take the rad in anyway, just to make sure I'm over all this "am I too hot I'm not sure!" nonesense.

michaeld

Here's a pic of the updated servo bypass for all to see:



Hose "A" (per previous labeling) connects to the driver's side (US models) of the heater core on the firewall.  Hose "D" is the feed hose from the driver's side of the engine.  In the MBz "heating water circuit" diagram JJCCP provided earlier in this thread, Hose "D" is labeled "a" and identified as the heating water feed.

Hose "B" connects to the passenger side of the engine.  In the MBz diagram, hose "C" is labeled "b" and identified as the heating water return.  Hose "C" connects to the heater core on the passenger side, as can be seen in the photograph.


There are two vacuum hoses that attach to the bottom of the servo.  I presume these would need to be plugged.  The golf tee you see is a possible plug for one of those.

After I am all finished, I might post this as a thread titles, "How to Bypass the U.S. ACC servo."  It will be dedicated to JJCCP, who has guided me through what for me would have been a hopelessly confusing process.  As often as these units "blow up," the bypass procedure ought to be documented.

jjccp

You did it! Nice job. I now appoint you the "Servo By-Pass King of North America."

I'm not sure from your picture but it looks like hose D might be kinked a bit (right near that orange dot thingy). Ok, now I see the orange thingy is the golf tee. Actually, you don't need to plug those two vacuum lines that go to the bottom of the servo. If you follow them they lead back up to the big vacuum connector that you just took off of the servo. In other words the other end of the line you plugged is still open, but doesn't make any difference at this time.

I'm probably wrong about D being kinked, because I know you're being careful. Remember your reason for doing the by-pass is to ultimately fix the overheating problem and you don't want to create other problems with the coolant flow. If you think you want to change this, simply rotate hose A so that splice is up higher and above the other splice, like in my picture. That way you don't need to tweak hose D so much. Probably a non-issue. The B to C splice looks perfectly un-restricted.

I went around and checked and tightened every single hose clamp that I could see in engine bay also.

If you want to get really crazy, you can clean up all the electrical connectors that you just took off of the servo and the aux pump with a little sandpaper or a dental tool.

Carry on. I'm hoping to see more progress Michael. I'm probably coming to California in the next couple of weeks and I might need to borrow your car. Just kidding about the borrow part, but I will be staying in Hermosa Beach if I come there.

Jim
1977 280 SE
1978 San Juan 23
1979 6.9 #6846

Tomi

hello fellows,

I had the servo cracked when I bought my car and I purchased the new servo which JJcp showed in his post. This has an aluminum upper body and a plastic underbody. After about a year of driving the under body cracked. I got a new underbody of aluminum from George Murphy for about 40 USD and now everything works good again. This servo is excellent when it works and I wish to keep it working as long as possible. It is more important in cold climates.
I hope that this aluminum body is more resistant than the plastic one.
When this fails I'll consider the electronic expensive alternative.
Tomi