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

wbain5280 · #10 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 · #11 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 · #12 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

Rahulio1989300E · #13 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!

McDiesel · #14 08-20-2006, 12:24 PM

YOU HAVE NOTHING TO LOOSE BUY TRYING A 3 DOLLAR BOTTLE OF BARS LEAK.. NOT THE ONE WHERE YOU HAVE TO DRAIN THE RADIATOR!

I had the same problem in my 1992 235k orig radiator turns out it was leaking from the temp sensor.. well not any more

pour the brown goo in the expansion tank.. fill bottle with water and shake it for a min and add it to radiator tank.. Drive the car for about an hour and then let her rest..

worst thing is you wasted 3 bux...
my 1998 i added it it to it before any leaks !!

300ESUPER · #15 08-20-2006, 02:34 PM

Phalcon51 thanks for all the info and the link to the insrtructions on how to remove the water pump.. I just removed the water pump at around 2 hours. I could not remove the belt by using the tentioner 13mm bolt so I had to pry it off (I know not the best thing). Everything else came out like butter. I removed the 13mm bolt and noticed that it came off the threaded shaft, I guess I need to purchase a new one. When I removed the water pump I noticed that the o-ring where the pump meets the block was as flat as a pancake in one spot near the bottom of the pump. I guess that is where it was leaking.

I think that the water pump is still in good shap and I only need the o-ring, but I am going to change the water pump anyhow (I do not want to go through this again).

Now I hope that putting it all back together will be just as quick and with no problems. I am going to buy the new pump on Monday and I am also going to purchase a new upper and lower rad hose and the 2" bypass hose.

The only problem I have now is getting the fan clutch to stay still so I can remove it to put the belt on (I still have the old belt wedged in there and need to remove it).

I will keep you guys posted.

Thanks Fab