87 560sl fuel pump noise - PeachParts Mercedes-Benz Forum

Two560Two · #1 01-08-2006, 10:11 PM

I have a 89 560SL with 29k miles and I want to buy another. I saw one in my local area. An 87 560SL with 54k mles. I looked at it and like very much but just have one question. The fuel pump on the 87 is louder than the one in my 89. My 89's fuel pump is like silent hissing. The 87 sounds a bit louder than usual. I drove the 87 and the car picks up great and everything but the noise just bothers me. I was thinking the fuel filters need replacing? Any input is appreciated.

Also the radiator was replaced on the 87 also for some reason. the owners told me that that is how they got the car. I had my mech check out the car and he told me it was in excellent condition and I should buy it. There is no bubble in the rad tank and the gaskets are in great shape. I was thinking that the oriignal owners put the wrong coolant and you know what happens to MB radiators if you put the wrong coolant! The sellers want $16k for it and its a good price for an SL with that mileage.

Strife · #2 01-09-2006, 12:01 AM

Quote:

Originally Posted by Two560Two

I have a 89 560SL with 29k miles and I want to buy another. I saw one in my local area. An 87 560SL with 54k mles. I looked at it and like very much but just have one question. The fuel pump on the 87 is louder than the one in my 89. My 89's fuel pump is like silent hissing. The 87 sounds a bit louder than usual. I drove the 87 and the car picks up great and everything but the noise just bothers me. I was thinking the fuel filters need replacing? Any input is appreciated.

Also the radiator was replaced on the 87 also for some reason. the owners told me that that is how they got the car. I had my mech check out the car and he told me it was in excellent condition and I should buy it. There is no bubble in the rad tank and the gaskets are in great shape. I was thinking that the oriignal owners put the wrong coolant and you know what happens to MB radiators if you put the wrong coolant! The sellers want $16k for it and its a good price for an SL with that mileage.

Although the pumps are supposed to make more noise when they reach end-of-life, there's probably some variation from pump to pump, and maybe even in the way that they are mounted. It seems very early for this problem.

Assuming no accident history, maybe the radiator broke (search on broken necks on radiators). This might be from the wrong coolant - this is a theory, or from the motor mounts being old (time, as sell as mileage will kill rubber, of course) and straining the hose between the water pump and radiator. If it broke while on the highway, the engine might have overheated and warped the heads. This is all conjecture - worth mentioning, hope I don't make you paranoid (also), other than that it sounds like a good price...I also want another, one I can drive in the winter.

ctaylor738 · #3 01-09-2006, 04:17 AM

Replacement radiators are pretty common in these cars for whatever reason. I agree with Strife that the pump noise is no big deal unless you find it annoying.

Two560Two · #4 01-09-2006, 10:02 AM

Thanks. Well I was just wondering about the pump noise beccause the one in my 89 560 is almost quiet just like light silent hissing. There is no accident history so I dont think that is why the Rad was replaced. The owner told me the Rad was leaking and so that is why it was replaced as I just asked them again today about it. hopefully I can get this car for $15 since I have to replace some dinged chrome moudlings and fix a leaking A/C that was fixed already. My mech told me to go for it and the problems he saw were minor fixes. I will keep you guys posted

Two560Two · #5 01-10-2006, 12:57 AM

SOLD! I got the SL for $15k and hope it will serve me well. I am going to get it in 2 days

Captain Scott · #6 01-16-2006, 01:29 PM

two560,

My 74 SL has a fuel pump that intermittently hums loudly, too. Not sure about the age and I have not seen/felt any fuel related operational indications, yet... So for now, until it dies or changes status, I'll just ignore it! Or at least until people start to ask me why my car is humming.

nobby · #7 01-16-2006, 11:35 PM

OK...so what happens to MB rads if the "wrong" coolant is used and what is the wrong coolant?

Strife · #8 01-17-2006, 01:09 AM

The general opinion is that "green" coolant causes plastic parts to become brittle over time, among other things (incompatibility with aluminum). The incompatibility with plastic has not actually been proven scientifically as far as I know but there seems to be a lot of evidence pointing that way. I'd use the MB coolant if possible - it's really not that much more expensive.