Oversize radiator and that bloody water pump 603 - PeachParts Mercedes-Benz Forum

Beirut Brit · #1 12-06-2020, 07:01 AM

Hi
Bif of a conundrum for the OM603 fanatics. I have a 603 in my 300 SDL which was dropped in at some point by a PO, as some of you have pointed out to me.

But i wanted to change the water pump as it sounds like its is not working well (grinding noise) but have reached a set back. To get the water pump off, of course one needs to take off the clutch fan. To do this, ideally, the rad needs to be lifted out. The problem i found though is that i have an oversized radiator, which is almost 9cm in width and has a lip on the bottom of it which catches against the side of the clutch fan when the rad is lifted up. It's really tight down there and i can't see any way of getting this radiator out without pulling out the AC radiator. But then again. I'm assuming that if i lift the rad up, and then tilt it 10 degrees or so towards the back of the engine, there would be - perhaps - room for the AC radiator to slip through the gap. Im guessing that the two lines going into the condenser are pressurused so i should expect escaping gas, right?

any thoughts from members who have also a 603 in a W126? Or have any experience of these over sized radiators? I can only think that when they dropped the six cyclinder beast in, the PO never thought of that tiny gap and removing the water pump one day, or the pully tensioner.

But let me share my thoughts about the water pump. Am i over reacting? Standing over the top of the engine you can just about here the pump. If i put a 60cm long scredriver to the water pump itself and put my ear to the handle i can distinctly hear a grinding noise. Is this normal? Or am i right to think about changing the pump?

As always, grateful for any advice.

best

MJ in Morocco

Diseasel300 · #2 12-06-2020, 09:44 AM

Grinding is never normal on a water pump. The bearings are done.

The clutch fan design on the 603's is absolutely STUPID. Whoever thought that stupid crap up should be dragged out in the public square and stoned until turned into a puddle of goo. Even with the proper factory tool, it's a nightmare of a job.

The fan can be pulled with the radiator in place. It's a tight fit, but it's doable. You need a pulley holding tool to keep the pulley from spinning. Take the fan shroud off and lean it back against the block. The bolt through the center of the fan clutch is an 8mm allen. There is a special tool to remove it with a breaker bar, but I have personally not had good success with it due to the metal being soft and distorting if the bolt is too tight. I drive the allen bit out of a socket adapter, sling an 8mm closed-end wrench over it, insert in the head of the bolt and use a piece of pipe as a breaker handle. Give it a sharp shove CCW while holding the pulley still and it'll break the bolt free. There is JUST enough room to get your hand in there to thread the bolt out.

Should give you clearance to get the radiator out. Don't remove the AC condenser if the AC is working. You're opening a whole can of worms and extra expense that isn't needed if you do that, and it isn't necessary to remove the water pump anyway. Pulling the radiator and clutch fan will give you plenty of access.

Be aware that the replacement water pump will be for a 606 engine (606 and 603 used the same pump). The difference is the bolt through the clutch. The 606 uses a slightly larger bolt with a Torx T55 head. You will need the bolt when you replace it (does not come with the pump). Now is also the time to replace the fan clutch if you think it's tired.

The correct radiator for the 300SDL is made of unobtainium and only aftermarket all-aluminum replacements exist nowadays. If you have an oversized radiator, it would be worth your time to figure out what it came from so you can source a spare if you need it. The other W126 radiators do not work with the 603 due to the slant of the engine. The fan interferes with the upper radiator neck on the other 6 cylinder and V8 radiators.

martureo · #3 12-06-2020, 11:03 AM

I would add that you should look for a decent water pump. Geba is one of the brands that I'll stick with as they tend to have the cast impeller rather than the sheet metal one.

You want the one on the left, not the right.

Beirut Brit · #4 12-06-2020, 11:19 AM

I would say at best the gap between the rad and the fan clutch housing is 10mm.

Do you think i could get a tiny alen key, customed chopped off piece, in there and turn it with a regular spanner?

Quote:

Originally Posted by Diseasel300

Grinding is never normal on a water pump. The bearings are done.

The clutch fan design on the 603's is absolutely STUPID. Whoever thought that stupid crap up should be dragged out in the public square and stoned until turned into a puddle of goo. Even with the proper factory tool, it's a nightmare of a job.

The fan can be pulled with the radiator in place. It's a tight fit, but it's doable. You need a pulley holding tool to keep the pulley from spinning. Take the fan shroud off and lean it back against the block. The bolt through the center of the fan clutch is an 8mm allen. There is a special tool to remove it with a breaker bar, but I have personally not had good success with it due to the metal being soft and distorting if the bolt is too tight. I drive the allen bit out of a socket adapter, sling an 8mm closed-end wrench over it, insert in the head of the bolt and use a piece of pipe as a breaker handle. Give it a sharp shove CCW while holding the pulley still and it'll break the bolt free. There is JUST enough room to get your hand in there to thread the bolt out.

Should give you clearance to get the radiator out. Don't remove the AC condenser if the AC is working. You're opening a whole can of worms and extra expense that isn't needed if you do that, and it isn't necessary to remove the water pump anyway. Pulling the radiator and clutch fan will give you plenty of access.

Be aware that the replacement water pump will be for a 606 engine (606 and 603 used the same pump). The difference is the bolt through the clutch. The 606 uses a slightly larger bolt with a Torx T55 head. You will need the bolt when you replace it (does not come with the pump). Now is also the time to replace the fan clutch if you think it's tired.

The correct radiator for the 300SDL is made of unobtainium and only aftermarket all-aluminum replacements exist nowadays. If you have an oversized radiator, it would be worth your time to figure out what it came from so you can source a spare if you need it. The other W126 radiators do not work with the 603 due to the slant of the engine. The fan interferes with the upper radiator neck on the other 6 cylinder and V8 radiators.

Beirut Brit · #5 12-06-2020, 11:56 AM

great but im a long way from changing the water pump as it looks like i have to take the engine out just to change it.

Quote:

Originally Posted by martureo

I would add that you should look for a decent water pump. Geba is one of the brands that I'll stick with as they tend to have the cast impeller rather than the sheet metal one.

You want the one on the left, not the right.

Usaguy · #6 12-06-2020, 12:21 PM

Quote:

Originally Posted by Beirut Brit

...looks like i have to take the engine out just to change it.

#1: How did they put that radiator in place?

#2: Worst case scenario loosen up the engine mounts and the tranny mount and just push the engine back to get enough room to remove the fan clutch.

Diseasel300 · #7 12-06-2020, 12:43 PM

Quote:

Originally Posted by Beirut Brit

great but im a long way from changing the water pump as it looks like i have to take the engine out just to change it.

The engine did not go into the car after the radiator. Something isn't right here, please post a picture of your setup. Sometimes a picture is worth a thousand words and can end rampant speculation.

Beirut Brit · #8 12-06-2020, 12:58 PM

the only way was when they put the new engine in. The PO dropped in the 603 engine. Probably the rad was already there

I think your worse case scenario is less extreme than mine. I was thinking how much you can damage the tiny fins of a radiator. If i forced a wrench down there with an 8mm key to release the allen bolf of the fan clutch, then i could get it off before pulling up the radiator, no?

Quote:

Originally Posted by christuna

#1: How did they put that radiator in place?

#2: Worst case scenario loosen up the engine mounts and the tranny mount and just push the engine back to get enough room to remove the fan clutch.

Beirut Brit · #9 12-06-2020, 01:00 PM

ok, i ll post some pics tomorow. But how can you be so sure that the engine didn't go in, with this oversided rad already installed?

Quote:

Originally Posted by Diseasel300

The engine did not go into the car after the radiator. Something isn't right here, please post a picture of your setup. Sometimes a picture is worth a thousand words and can end rampant speculation.

ah-kay · #10 12-06-2020, 01:16 PM

Quote:

Originally Posted by Beirut Brit

I would say at best the gap between the rad and the fan clutch housing is 10mm.

Do you think i could get a tiny alen key, customed chopped off piece, in there and turn it with a regular spanner?

I have done it many times with my w126/w124. Just use an Allen key to undo it. Use the L shape Allen key and you may need to shorten the small L a bit to make it easier. It is a tight fit but can be done. You also need to extend the long L with a socket to give you more leverage.

Good luck.

Beirut Brit · #11 12-06-2020, 01:24 PM

The radiator is not a normal one. It is over 8cm wide and there is only 1cm of space between the clutch fan and the surface of the radiator.

Perhaps the original set up, with the 5 cyclinder diesel engine would have been fine. But with the 603 engine and the oversized radiator, it's too tight.

Quote:

Originally Posted by ah-kay

I have done it many times with my w126/w124. Just use an Allen key to undo it. Use the L shape Allen key and you may need to shorten the small L a bit to make it easier. It is a tight fit but can be done. You also need to extend the long L with a socket to give you more leverage.

Good luck.

ah-kay · #12 12-06-2020, 01:37 PM

Quote:

Originally Posted by Beirut Brit

The radiator is not a normal one. It is over 8cm wide and there is only 1cm of space between the clutch fan and the surface of the radiator.

Perhaps the original set up, with the 5 cyclinder diesel engine would have been fine. But with the 603 engine and the oversized radiator, it's too tight.

W126 always has a OM603 engine. Your radiator is 8cm thicker? Are you sure? How could it fit? Any fan shroud there? There is no way the fan shroud can fit properly into the bottom slots. May be remove the radiator first. If ithe thick radiator could be installed then it could be removed.

speednjay · #13 12-06-2020, 01:39 PM

Don’t even need to take the fan off. Just pull the radiator straight upwards

83w126 · #14 12-06-2020, 02:34 PM

Remove the fan first, then the shroud, then the radiator. You need something similar to the links below to do it.

https://www.harborfreight.com/hand-tools/sockets-ratchets/14-in-38-in-drive-long-reach-dual-flex-head-ratchet-67994.html

https://www.amazon.com/Titan-Tools-16141-Profile-Stubby/dp/B005CGZOBW/ref=sr_1_5?dchild=1&keywords=short+8mm+allen+socket&qid=1607282932&sr=8-5

https://www.northerntool.com/shop/tools/product_200678218_200678218

Diseasel300 · #15 12-06-2020, 02:44 PM

Quote:

Originally Posted by Beirut Brit

The radiator is not a normal one. It is over 8cm wide and there is only 1cm of space between the clutch fan and the surface of the radiator.

Perhaps the original set up, with the 5 cyclinder diesel engine would have been fine. But with the 603 engine and the oversized radiator, it's too tight.

I've mentioned it in previous threads you've created and I'll repeat it here:

Create a signature line showing what you have. This is not a stock car and is far from a stock configuration. Calling it a "300SDL" in all of your threads will get you nothing but confused answers and speculation about things your car does not have and does not resemble.

You need to run the VIN and figure out what year and model your car originally was so that chassis and engine/drivetrain issues can be adequately addressed. Providing photos of your very non-standard car is also very helpful to people trying to help you.

Keep in mind, the 300SDL was a US-Market ONLY vehicle for 1986 and 1987 model years. All of them were turbocharged OM603's and automatic transmissions. The W126 had a production break in 1985, so earlier chassis are mechanically similar to 1986+, but the wiring/electronics/switching/engine management are all *VERY* different.

By not declaring in your originating posts that your car is a strange engine-swap job, not providing photos of what you're asking about (since you aren't using stock components), and by calling the vehicle by a model number that it isn't, you're not doing yourself any favors getting concise and helpful troubleshooting advice.

Please - create a signature line showing what your car is so that if you forget to declare it in your originating posts or in your replies, it will always be posted so that people reading and replying to your threads and comments understand what it is you're working on.