Rad leak 1989 300E - PeachParts Mercedes-Benz Forum

300ESUPER · #1 08-16-2006, 09:28 PM

My temp gauge in my 1989 300E went from 80 to 120 today. I then check under the car and noticed that there was a pool of rad fluid on the ground.

I check all the rad hoses, the overflow tank and the radiator and found nothing. I drove the car on ramps and removed the plastic cover and rad fluid fell everywhere. After removing the plastic guard I noticed rad fluid allover the oil pan and the side of the engine, but still do not know where it is coming from.

I am thinking it might be the water pump. How would I now if the water pump is leaking? First off where is it located, how do I test it and finally if needed how do I replace it?

Thanks

Fab

300ESUPER · #2 08-17-2006, 06:30 AM

Just to add to my post, the car only leaks when the car is parked and off. When the car is running there is no leak. When the car is parked on a decline or on level ground the car leaks, when I put the car on an incline (like on ramps to check the car) there is no leak (that is why I probably did not see anything).

Please help

Thanks

Fab

J.HIDALGO · #3 08-17-2006, 06:37 PM

Most likely is the water pump. The water pump has a pee hole on the bottom of it. If it is leaking, it is time for a new one. It is hard to see! As far as replacement...do a search there are some pictures somewhere. I bought a special tool that makes it easier to change without removing too many pieces. As far as the location, it is connected to the engine block towards the front, on the driver's side. You will see a small hose 2 -3" connected to it...
Good luck!

300ESUPER · #4 08-17-2006, 09:31 PM

Thanks for the reply J.HIDALGO. There is a lot of antifreeze coming out. Would there be a lot coming from the pee hole of the water pump? ANd is there anyway I can see this hole.

Thanks,

Fab

Phalcon51 · #5 08-18-2006, 12:24 AM

There's a picture I posted some time ago showing the weep hole location on the water pump off my 86 300E here. It's at the bottom of the page.

You'll need a couple of inexpensive special tools to do the job. One is a stubby, 3/8 drive 8mm allen socket for removing the center bolt from the fan clutch and the other is a piece of bent rod for holding the fan clutch from turning while you loosen or tightern the bolt. They're both available from Performance Products for $7.15 and $16.00, respectively. I can't find them on their web site, but they're both on page 156 under the heading "Serpentine Belt Tool" in their latest catalog. You can call them at 800-243-1220 and request a catalog or order the parts. The allen socket is part #58-019 and the fan clutch holding tool is part # 58-021.

Be sure to replace the short hose between the w/p and the cylinder head, and while you have the upper hose off, check the radiator neck to see if it's the newer reinforced type. There should be a metal sleeve inside the neck. If it's not reinforced you might want to consider doing it yourself with some thin wall copper, brass or aluminum tubing and some judiciously applied JB Weld. Check the neck closely for any sign of cracking. They can be quite brittle when they get old, so handle it gently. If it is cracked, replacement is in order in the near future. When they break, it's usually a sudden catastrophic failure with no warning. The Behr radiators from FastLane should be the new reinforced type.

Hope this helps.

Rahulio1989300E · #6 08-18-2006, 12:48 AM

WHOA! WAIT A MINUTE!

Sorry, I had to get your attention.
My car had a leak EXACTLY like yours. I also thought it was the water pump, I replaced it, but that was not it. My car only leaked when turned off from a normal operating temperature.

For my car, it turned out to be the heater hose at the back of the cylinder head. The hose clamp had compressed the hose right where the clamp's screw was. After all these hot and cold cycles, I am guessing that it finally gave up. I replaced it and wha la! No more leak.

Drive your car around till it gets hot, then wear a thick glove of some sort, grab a 100% clean shop rag and dab the bottom of that heater hose where it connects to the cylinder head with the rag, see if it gets wet.

The yellow circles in the picture shows the hot coolant landing on my oil filter and coolant pipes.

The red is circling the hose that gave me the trouble.

300ESUPER · #7 08-18-2006, 10:52 PM

Thanks for all the replies. I check the hose at the back of the engine and it was dry. I used a coolant pressure tester on my car and I noticed no leak anywhere. So I decides to take off my airfilter box to see if I can get a better look to see if there is a leak. I noticed that there was water/antifreeze flowing down the right side of the engine block, down the oil pan and onto the floor. (right side if you are standing infront of the engine). It looks like it starts near the back of the water pump but I cannot be sure. Is there anything else that might leak from there. Would the water pump leak when the car is on or off beacuse me leaking seems to happen when the car is off?

What would cause the water pump to leak?

Thanks,

Fab

Phalcon51 · #8 08-18-2006, 11:44 PM

Can't think of anything else likely to be leaking from that location besides your water pump. How many miles are on the car? Is this still the original w/p? If you have a mechanic's mirror (small mirror mounted on a telescoping handle) and a flashlight you can probably see the w/p weep hole with the engine off and check for any evidence of leakage.

300ESUPER · #9 08-18-2006, 11:50 PM

This is the original water pump. The car has 727,000km all original.

I will check with a mirror to see if it is leaking from the weep hole. I will keep informed.

Thanks

Fab

Phalcon51 · #10 08-19-2006, 12:26 AM

Wow! That's 451,736.86 mi.!! Give that poor car a new water pump, at least. That's really quite phenomenal. The typical water pump in most cars is toast by 100-120k miles or sooner.

wbain5280 · #11 08-19-2006, 01:11 AM

[QUOTE=Rahulio1989300E;1249769]WHOA! WAIT A MINUTE!

[SIZE="2"]

Hey guy, I noticed your dad has an S90 w/125K miles. He has replaced the timing belt at 105K right? Also, make sure the serp belt gets changed regularly as that can also cause timing belt problems if it breaks.

OOPS sorry, those vintages have 70K timing belt changes cycles. My mistake. I was thinking about the ex's V70.

david s poole · #12 08-19-2006, 11:18 AM

the leak you describe is common and comes from the rear o ring where the pump connects to the block.you have to remove the pump to change it.better buy pump and top by pass hose[short one which also can only be changed with pump off] good luck david poole european performance dallas tx.

300ESUPER · #13 08-19-2006, 08:02 PM

I wanted to start taking out my water pump and found out that the 19mm bolt that you turn to loosen the tention does nothing but turn in its spot. I cannot get the serp belt off. Is there any suggestions. Also now I am going to have to replace the tentioner any idea on how to do that?

How many gaskets are there for the water pump? I also noticed that there was a metal pipe that goes to the water pump that is held on with 1 bolt, is there a gasket for that also?

One more thing, is there anything I should now about taking out the water pump or is it straight forward?

Thanks Fab

Phalcon51 · #14 08-19-2006, 09:57 PM

First you have to loosen the 19mm central bolt and then loosen the tensioner adjustment nut on top. Be aware that it's reverse threaded. Once the tension is off, you should be able to move the tensioner by hand by the roller and remove the serpentine belt. The tensioner is held in place by the large central bolt. It must be removed completely and then you can withdraw the tensioner. Here's a link to a thread on properly adjusting the tensioner as well as how to determine if it's time to replace it.

In regards to the metal pipe, the newer water pump (starting from engine #12-268716 onwards) requires that you use a newer metal drain pipe as well as a newer upper radiator hose.

There are 3 o-rings used on the w/p: one to seal it to the block, one to seal the thermostat cover and one to seal where the metal pipe attaches. They're all listed in the parts list under "Cooling System" in PartsLane (see "Buy Parts" link at top of page)

Removing the w/p is pretty straight forward, but as I recall you might need a special wobbly socket to get at one of the bolts at the top rear of the w/p.

I believe that you also have to unbolt the power steering pump and move it to the side. (break loose the p/s pulley bolts before you take the tension off the belt or else use a strap wrench to hold the pulley after the belt is removed.)

Here's a link to a rather comprehensive discussion on replacing the w/p.

And here's another link with a link to some pictures showing some of the problem areas in the job.

All in all, if things go well it should take you an afternoon or so to replace the pump.

Hope this helps

Rahulio1989300E · #15 08-20-2006, 10:57 AM

[QUOTE=wbain5280;1250810]

Quote:

Originally Posted by Rahulio1989300E

WHOA! WAIT A MINUTE!

[SIZE="2"]

Hey guy, I noticed your dad has an S90 w/125K miles. He has replaced the timing belt at 105K right? Also, make sure the serp belt gets changed regularly as that can also cause timing belt problems if it breaks.

OOPS sorry, those vintages have 70K timing belt changes cycles. My mistake. I was thinking about the ex's V70.

Yeah, we replaced the timing belt at 65K then at 133K to be on the safe side.
Serp belt was done at 100K.

Thanks for the reminder!