SL65MONSTA

I have a 2004 SL65 when I accelerate above 2500 rpm the steering goes hard and the power steering stops working, as soon as the revs drop down it slowly comes back to normal functioning. I initially thought it could of been a water leak dripping onto the serpentine belt, but I have fixed that leak and it is still doing the same thing. It could possibly also be another pulley that is seizing up and not allowing the belt to turn or jumping off the power steering pump pulley. With the SL V12 which pulley is most common to failure ? or does this sound like a power steering pump failure?

Thanks in advance guys

Plutoe

You either have a faulty rack or pump!!

PS: if it jumped a pulley don't you think you would have noticed that!!

SL65MONSTA

Sorry I may have not been very clear. If the serpentine belt was intermittently lifting of the pulley (jumping) disengaging momentarily the pump. I think your 100% right on its either one of the rack or pump, next question to you I guess would be how to determine which one it is , or is there a post about it?

* also if the power steering pump is seizing which i think it is because a screeching noise is heard when it stiffens (belt noise) wouldn't one think that being a tandem pump an ABC light would be thrown , or it would also affect the ABC system somehow?

Could it also be another pulley seizing up that in effect is making the belt slip, thus not engaging the PS pump?

Thanks for your help

Plutoe

is The water is very shallow regarding the belt--make sure it on and all torqued accordingly---the deep water is the testing of the rack\pump---that is not a DIY and takes testing equipment which I doubt you have or access to---so what do you do when you are about to drown--you scream for a life jacket. In this case the life jacket is a reputable shop that knows MB's and can provide you with answers.

Alternatively do a WAG and change the pump!!!

SL65MONSTA

Lol what is a WAG? There is a screeching noise coming from the belt , so it's definetely the pump seizing but not sure if it's the power steering pump seizing or another pulley seizing causing the belt to disengage of the pump pulley I have searched and searched the forums."NO WRITE UPS ABOUT IT!"

Rudeney

WAG = Wild-Asssed guess. I know it's a totally different engine, but my C240's M112 mae a horrible "clucking" noise when turning the steering wheel fully to the locks. I thought it was a bad pump, but it turned out to be a bad spring in the tensioner pulley. Another time, I had hard steering, a voltage warning and poor AC performance. Tat was a few days before the idler pulley broke apart, which shredded the belt and "deposited" it inside the alternator.

I'd remove the belt and thoroughly inspect is, the tensioner and two idler pulleys. Any feelings of bearing roughness or surface defects on the pulleys and I'd replace them. Make sure the tensioner spring feels tight. I am not sure of what torque to expect when pulling on its dead-man nut, but I'd guess at least 50Nm.

SL65MONSTA

It seems there really is no way to tell which pulley is seizing up , I taped a multimeter onto my windshield and connected it to battery terminals , I can eliminate the alternator pulley of being the culprit. I have a wall cavity camera I purchased for $10 of eBay with a 5 metre cable, I'm going to tape it facing the pulleys individually starting with the power steering pump (being the obvious culprit) and will drive it to perform the seizing symptoms again , the camera program that comes with it allows recording , will keep eyes on road and then view footage after stopping , if that pulley is seizing up then that's my problem, it beats changing random pulleys! "Less work and less money" will let you know how it goes guys

SL65MONSTA

Update guys , installed camera with a zip tie in engine bay went for a drive , pulley is intermittently seizing up. Then moved the camera to watch the belt and the other pulleys to see if one was seizing , nope there all working fine. Culprit is the power steering pump, thanks for your help anyway guys

BlownV8

The tandem pump is very expensive new. You may be able to find a rebuilt unit in your country or the US. Welcome to the world of ABC suspension and components.

SL65MONSTA

They rebuild them for $200 in Australia, its not too bad. Lets hope I never have to replace parts on the ABC :/

BlownV8

The tandem pump is considered an ABC component. It usually starts with a blown hose that bursts and then the pump grenades and then the metal particles infect the system.......then the valve bodies get clogged and..........then the metal particles reinfect the new pump and the new pump grenades and it starts all over again in a big loop.

ItalianJoe1

When you're in there make sure the tensioner is good and the belt is in good shape. The P/S pump has one of the highest loads of any accessory, a weak belt tension condition will start to show up there first usually, before you lose the alternator or a/c or an idler pulley.

It very well could be the pump seizing up but that's unlikely to be an intermittent issue.

SL65MONSTA

Upon closer inspection , turns out it's not the pump at all and many of the power steering places I called said Mercedes power steering pumps hardly fail, turns out to be a hole in the hose that was spraying water making the belt slip and pump not rotate. Did the most dangerous test, ran the car dry , took her for a drive around the block, what do you know power steering working just fine, it was the coolant /water spraying onto the pulleys. Wow and I was just about to buy a new pump or remove mine to get it reconditioned, new hose is on its way. Next problem to solve is why is the hose bursting , it's not the first time it's burst too, it's previously burst in a different spot and I temporarily placed a pipe and two clamps to seal it, maybe because I'm only running water in the testing stages, I've been through about 75litres of coolant every time a hose bursts or the hose comes of the radiator. It could of been a bad thermostat , or because there was no thermostat at all? But that's been fixed and still a burst in the hose, I'm thinking maybe because I ran water only it was not cool enough ?

ItalianJoe1

If the hoses are bursting it's overheating or your connections are not good, clamps not tight, etc.

The fans fail all the time on these cars as they age, and don't always set codes. I had mine intermittently not working on my first CL and ended up just replacing it after the car almost overheated on me when I got stuck in traffic one day.

SL65MONSTA

I'm hoping that the hose is brittle and fracturing in multiple places, I will make sure I tighten the clamps up I remember once one of the clamps was not fully tightened and could well be why it's burst. Fan did fail also and swapped it out of my s600 I have in my shed for spares. Thanks for that

ItalianJoe1

If you haven't replaced the hose, do it. Re-tightening clamps won't solve a hose that's old and not sealing properly, it just moves and leaks again once it gets hot.

SL65MONSTA

Will do ^, thanks.
My biggest fear is replacing the hose only to have the new one burst and it is something else , such as faulty water pump (although that was replaced 5 months ago) or high compression , head gasket, or internal blockage, faulty thermostat, or just fluid issue

Rudeney

I once had a car where I had to replace all the coolant hoses. One started leak, which I replace,d then another, etc. Once all had been done, everything ran well for many more years. That was over 30 years ago, back in the "good old days" when hoses and belts were good for only 30K miles or so. Today's rubber products are much more durable and long-lived. My 15-year-old C240 with 132K miles has all the original coolant hoses. The only cooling part that failed was the reservoir. Hopefully yours is just a defective hose and all will be well after replacing it.

ItalianJoe1

So, pressure test the car. If it can hold 15 psi for an hour there aren't any leaks, and your issue is an overheating condition. If it's losing pressure, solve the leaks first. Leaks cause overheating because without the proper pressure, coolant boils too easily and you get air in the system, which doesn't transfer enough heat to cool things down.