clydem

Had the MB320CLK at an indy for a rattle that I thought was a heat shield. He thought one of the cats. After getting it in the air he said no, it was the idler pulley which I replaced like 1.5 years ago. He replaced it & the engine mounts (2005 w 110K on the odo).


Then he showed me - car down on the ground, engine on, in park, & turn the steering wheel to extremes, the engine lifts up from torque significantly. He suspects the power steering pump is going and that's what took out the idler pulley early & will do it again.


So anybody else - if you could - do the same - wheels to the extremes, does the engine lift quite a bit?


Thanks.

Yidney

Well now you have me curious. Can't wait for Rodney to weigh in on this. I'm not following the principle behind either the engine lifting or the idler pulley going bad. Which part of the pulley was bad - the actual bearing on the pulley, or the spring mechanism that allows it to move side to side?

mrbobby

What's going on with the engine "lifting significantly" when the engine mounts were replaced only a year ago? When you sit in the car and turn the steering wheel do you feel any vibration or chattering? It sounds as perhaps were guessing at the problem rather than diagnosing the problem. Just my $.02. Good luck with the repair.

clydem

That's why I posted. The engine lifting doesn't make much sense to me either on the PS pump. But I figured, 100+ miles, sure the rubber on the mounts might be going. Now I'm wondering if he really had to replace the mounts or he guessed. But even on the new mounts, the engine lifted. I'm asking folks if maybe this is normal behavior. I wouldn't think so. I've never seen another car do this.


I can tell you that with the idler pulley replaced, the engine is quieter without the metallic rattle I heard.

Yidney

I tested my car, and it behaved as expected - the engine just sat there. You do get an initial optical illusion of movement because these cars have so much caster that the entire front end moves up and down as you steer from lock to lock. But even if I had a defective steering pump, I just cannot see the physics that could cause the engine to move. The power steering pump has very little mass, and is off to one side. Even if it were about to seize up I cannot see how it could move the engine. And while I do not question whether your idler was bad, I do not see how the pump caused it, although that is more plausible than engine movement. But maybe Rodney has an explanation of how this could occur.

clydem

A second set of eyes on the issue....thank you.
I should be taking it for a 2nd opinion tomorrow.

Rudeney

A bad power steering pump would not cause any lifting of the engine. This is either bad engine mounts, or as Yidney says, it could just be an illusion due to the entire car moving.

As for the noise, when the spring in the tensioner goes bad, it tends to make a "clucking" noise, especially when loading up the PS pump. I've replace two on the C240 and it's time for another one. ADvance Auto sells it with a lifetime warranty, so all I have to do is take it out and swap it.

clydem

Let me see if I can video it.

Yidney

And even if the mounts are bad, I'm not understanding why that would cause the engine to move while idling in park just because you turn the wheels. Where is the torque on the engine coming from?