87 190e 16V Water pump failure symptoms
 

I have a shrieking sound coming out of the area around the drivebelt. It has progressively gotten louder. It starts making the noise a few minutes after the engine is started. I thought at first the belt was loose. I tightened the belt a little bit but did not help any. After listening closely, it sounds like it's coming from the water pump. Has anybody have any experience similar to this? Is it the water pump? What does it take to replace a water pump?

Another thing, when I tightened the belt, I'm not sure if I overtightened. The marker is broke. How can I check? Any advice.

If the water pump is failing as you describe it will be leaking profusely shortly. The shaft seal can make noise like this if it is operating un-lubricated, and it will very shortly wear out. The seal is normally lubricated by the coolant, so, if you have changed the coolant and either used an anti-freeze that is not compatible with the engine materials, or not used any anti-freeze at all, you may be stressing out the seal. However, I think it is more likely one of the pulleys, idlers or other driven components, might have a bad bearing. I would suspect the idlers first. Try loosening the belt entirely and turning the idler and other driven equipment pulleys by hand. Good luck, and I hope this helps. Jim

Thanks a lot. That's quite helpful. I will do that. I'll check out the idler and other pulleys after loosening the belt. Is the idler the same as the tensioning roller?

I just changed the waterpump on 87 MB 190E 8V 2 weeks ago. Before i changed the waterpump, i also think that the noise came from the belt or tenioner.....

After cold started few mins later, it starts very noisy. When you press the gas, the noise becomes louder. Ended up i changed the waterpump and whole car quite!! Hope that this case can help u out.

That sounds exactly like what I'm experiencing. I'm quite certain that the noise is coming from the water pump but I don't see any leaks. I'll loosen the belt and check the other pulleys including the tensioner, just to be sure. Then I'll tackle the water pump.

How long did it take you to replace the water pump. I know you have to remove the fan, radiator and thermostat housing. Seems like a lot of work. Any tips, shortcut, things to look out for.

on my car, it took about 3 to 4 hours to replace. I took off the fan blade, alternator, thermostat housing and fan shoulder. Don't need to take off the radiator.

Water pum leaking after new install
 

Hey Jeff,

I just replaced my water pump this weekend. You're right. It's pretty straightforward. The only problem is, I still get some leaks coming out of it. I'm not sure what the torque specs are for the bolts that hold the water pump. I must not have tightened it enough. I'm afraid that I might over-torque it. I will have to take it all apart again. Should I replace the gasket with a new one. What's the best gasket to use. Any advice.

I also noticed that the engine is running pretty cold, around 50 on the temperature gauge. It used to run closer to 80. Plus I'm not getting enough heat. Could I have screwed up the thermostat. Any ideas.

Do a search on coolant filling to avoid air pockets in cooling system.

I changed mine months ago due to noises that I actually thought were the timing chain! I just tightened mine snug and a hair more. Make sure you seal was on all the way, it was a bugger to get in there as it kept moving on me before I got enough bolts in to hold it in place. No leaky for me afterward.

Thanks, I'm going to do that. I'll have to take it all apart again to get to it and tighten the bolts a little more. You're right about getting the gasket in place. That was pretty tricky making sure the bolts are through the gasket holes while holding the pump in place.

Also, thanks for the tips on the coolant problem. I read most of the messages regarding bleeding the cooland after refill. I tried the advice on the emails and it worked. I would not have thought about the air pockets ar all. That never happened to me in other cars. Anyway, thanks for all the help. This forum is great. Lots or experienced, knowledgeable and helpful people.

It could be a noisy belt, mine was. Its a real easy test: while the engine is running and squealing pour some water on it. If it is the belt it will be quiet for a few seconds until it dries out. Belt dressing is a quick temporary cheep fix, a new belt is the permanent fix