Doohickey on coolant hose - PeachParts Mercedes-Benz Forum

GlennCraven · #1 09-06-2007, 02:35 AM

Nice, educated-sounding thread title, huh?

My 1983 300D with an engine from an '85 has (as I'm sure all engines of this era do) these interestingly bent, short hoses to carry coolant from the back of the cylinder head area to a point on the firewall. The hoses were mated via a plastic 3/4-to-3/4 connector with a screw-off cap (with Prestone verbiage) that the guy at the radiator repair shop said was intended to let you thread-on a garden hose and flush the whole system.

That doohickey (the Prestone-capped thingamajig) cracked and developed a hole, dispensing coolant all over the back side of the engine, prompting me to make a hasty halt in a cloud of steam.

I replaced the cracked Prestone-capped thingamajig on Tuesday with a straight piece of 3/4-to-3/4 plastic heater hose connector from Advance Auto Parts. ... That piece broke in a day. I was blowing coolant all over by Wednesday evening. ... The connector piece actually broke *inside* the first piece of the hose it was connecting (the point from engine to connector, not connector to firewall region). There's broken-off stub o' connector in that hose. Not quite sure how I'll get that out.

What to do? Get another piece of plastic? Was this one too cheap and is there stronger/better? ... Is this indicative of some more serious problem with the cooling system? ... Is the car getting too hot or building too much pressure inside the system?

I only drive the car in three- to maybe 10-mile spurts around town/county, usually several hours apart.

I'm not a dummy but I'm no ace mechanic, either, so I ask these potentially stupid questions.

Thanks for sharing info and answers.

-- Glenn

running-snail · #2 09-06-2007, 07:15 AM

I share your mechanical abilities/inabilities but:

I have read numerous reports about failures of these radiator flushing t-fittings. I have one, but it goes on my car(s) to flush with some generic coolant hose attached, then after finished the old hose goes back on.

I would click the BUYPARTS tab above, or send a note to Phil and ask if he can source a new hose for you to replace the one you have.

Can't offer anything further on the subject - others will.

JimFreeh · #3 09-06-2007, 07:23 AM

Quote:

Originally Posted by running-snail

I share your mechanical abilities/inabilities but:

I have read numerous reports about failures of these radiator flushing t-fittings. I have one, but it goes on my car(s) to flush with some generic coolant hose attached, then after finished the old hose goes back on.

I would click the BUYPARTS tab above, or send a note to Phil and ask if he can source a new hose for you to replace the one you have.

Can't offer anything further on the subject - others will.

Just remove it by replacing the hose.

Jim

Ryan Z · #4 09-06-2007, 09:04 AM

Replace hose or get brass double barb connector from mcmaster.com
#91355k87 $12.90 for package of 5. Pricey, but long lasting.

---------------------
1984 MB 300 SD Turbo

kerry · #5 09-06-2007, 09:46 AM

The brass connectors are available at most local hardware stores.

GlennCraven · #6 09-06-2007, 10:13 AM

Thanks, everybody. I'll probably go with the brass connector (which should be available at the Ace Hardware near my workplace, where the car sits ... ) rather than trying to replace the whole hose.

But I guess, Jim, you're saying there is a straight hose option with no connector?

And I guess from everybody's lack of general distress that this is fairly routine parts-breakage, not a sign that something's about to fall (any further) apart?

Again, guys, thanks!

#7 09-06-2007, 10:30 AM

Quote:

Originally Posted by GlennCraven

And I guess from everybody's lack of general distress that this is fairly routine parts-breakage, not a sign that something's about to fall (any further) apart?

I have replaced that hose on my 82, it tends to get pushed around when you replace the oil filter on mine. The problem isn't the hose, it's the plastic POS that someone hacked into it. I would probably just replace the hose, but a metal connector should work just fine too.

tangofox007 · #8 09-06-2007, 11:02 AM

Quote:

Originally Posted by GlennCraven

But I guess, Jim, you're saying there is a straight hose option with no connector?

The flush fitting was not original equipment. The original one-piece hose was cut (and, most likely, a short section of the hose was removed) in order to install the flush fitting. The correct hose is not straight, but it is one piece.

http://catalog.worldpac.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=2650Q36L326A0NRQJY&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1983&product=R3030-16302&application=000027632

FRANKNBENZ · #9 09-06-2007, 07:12 PM

I noted that one of these Prestone flush kits was installed on Grey Ghost by the PO. No trouble, in fact I just did a total coolant flush last week with it...pretty neat. An OEM hose bent the right way is of course the best way to go, but if you wish to substitute, you could do a Home Depot special by sweating some copper pipe, a Tee, and fittings ending in a bronze male hose bib, with cap and washer. Just make it look like the Prestone assembly.

The thread postings respond to several replacement solutions. I mentioned the plastic assemby in mine works fine and stays dry. I would take a moment and try to determine how yours failed. Overtightening of the hose clamps could do it. Maybe you have excessive engine wobble that could have fatigued to failure what might have been already poorly installed. Check your engine mounts and shocks.

Good luck.

GlennCraven · #10 09-08-2007, 05:33 PM

Quote:

Originally Posted by FRANKNBENZ

I would take a moment and try to determine how yours failed. Overtightening of the hose clamps could do it. Maybe you have excessive engine wobble that could have fatigued to failure what might have been already poorly installed. Check your engine mounts and shocks.

Good luck.

Interesting that you mention this. Just a week before I had the engine mounts replaced because I *was* getting excessive engine-wobble. The plastic piece might have already been breaking at that point, but it sure didn't finish breaking until after.

However, now I have a bigger woe.

I replaced the plastic T connector with another plastic pipe. It broke within 36 hours; seriously. It fractured inside the hose portion running from the engine to the connector. I was again brought to a halt in a cloud of steam.

I left the car at work and the next day returned with a metal 3/4-to-3/4 piece from Ace Hardware. It wasn't brass, but was some sort of pot metal. I figured, however, that it wouldn't break -- something else would break first.

Well, apparently "something else" did break.

I have a leak under the front of the engine, general vicinity of the water pump. It's a steady leak that doesn't really seem to change much whether the car is idling or shut off entirely. It's a fast drip -- not quite a steady stream, but close.

Did I blow a water pump gasket? ... Was there somehow too much pressure on this system? Overfilled with coolant maybe? ... I try not to do that sort of thing, but I'm half-moron sometimes when it comes to cars.

Anyway, the leak seems to be above the oil pan and somewhere beneath the thermostat housing, sort of in the vicinity of all the belts and pulleys. That sure seems to be water-pump-vicinity to me. I guess I need to get it to somebody who can lift it and maybe they can figure out better than I.

Or should I just buy a set of ramps and go about replacing the water pump and gasket and see if it stops? Advance sells a remanufactured Beck-Arnley for $35 and a new one for less than $60. (I see from other threads the fasteners are hard to reach and easy to round-off if you use the wrong tools.)

Thanks,
Glenn

LUVMBDiesels · #11 09-08-2007, 06:53 PM

If the leak is coming from the thermostat area, it might not be the water pump. The thermostat housing is attached to the block with two bolts (near the EGR valve) and has a gasket. It could be leaking from there. Another leak source is the short inch and a half hose that attaches to the thermostat housing. I know Phil here has this hose as he just sold me one.

A water pump leak would be at the front of the engine right below the pump. It would seem to leak and then stop leaking at random, at least mine did that, as the pump rotates and the weep hole is sealed and unsealed. To check this, put a bunch of clean paper towels right under the water pump.

With a cooling system like yours, and as mine was, it seems that every weak link you replace only reveals the next weakest link. I ended up replacing all my hoses just to be sure of them. Of course, once I did that the radiator blew, but replacing that is actually very easy

Good luck!

GlennCraven · #12 09-09-2007, 02:56 AM

We looked for the leak in the dark (me and a couple of guys at work and me by myself in the daylight) and I think it's from the pump, but I'm not sure. I guess it could be above there. I'll try to get another look Sunday. Maybe I'll lift it with the floor jack.

FRANKNBENZ · #13 09-12-2007, 10:40 PM

Don't want to sound too CSI, but when you had the failures on the Tees, did you reconstruct them to determine if all the bits and pieces were present and accounted for? I hope you do not have a chunk of gunk floating about in there that may have gotten to your Wpump. This is akin to a thrombosis hitting the heart.

Regarding the metal used in your substitute pipe, I am neither a metallurgist nor a chemist, but I do know that in diesel plant systems we never use galvanized pipe to push fuel...always black pipe or fiberglass. Again, on diesel fuel systems the fuel somehow interacts with the zinc in the galv and causes flakes to break free. Injectors and pistons tend not to like that much.

Good luck finding the leak. R&R-ing a pump on Volvo took me about an hour.