Originally Posted by Playdrv4me
I take it this means it's shot?

Disconnected the electrical supply from it completely the other day and drove around all day, noticed no difference in acceleration at *ALL*, so I'm assuming it's done for.

Also someone suggested it coule be responsible for lurches when cruising too, which its been doing more now and at lower speeds, like 30-40mph all of a sudden Ill lurch forward all of a sudden for just a second. This is not the same as the tiny lurch I was talking about in another thread when just taking off, but this one is when actually cruising.

Anyway, I guess I'll be getting a johnson pump eventually or a Ford Lightning SVT unit and adapt it on the cheap.
--------------------------------------------------------------------------------------------------------
I am also having the lurches when cruising. I took it in to the dealer but they couldn't find the problem because their not a computer light or code. Sure wish I could find the problem because it's the pits. Drove all the way to and back for W.W.D. cruise last week end with this happening. Can anyone help????????
Ask the need wings mech. about it but he didn't no.

 

Sounds bad.
However a lurch is unusual.
Typically (mine happened more at highway speeds) when you give it gas it falls on is face. Feels more like a Prius at the dragstrip than a supercharged vehicle.

 

Roky & Play:

I would be careful jumping to the pump-is-bad conclusion. Remember a bad pump only causes loss of power when the engine and supercharger are hot. In fact, the ECU shuts down the supercharger when the IC coolant exceeds a certain temperature.

If your car runs fine when the engine is cold, but runs like crap when the engine is hot, then you likely have a pump problem. But if it runs the same all of the time, it's not the pump.

That said: replacing the pump is a relatively cheap thing to do, and it will eliminate one possible problem.

 

Not entirely acurate - but a somewhat valid point.
It does get worse as the engine gets hot.
But the air temp from the s/c is the critical factor.
Even a relatively cool engine running high boost (and high AIT) will puke with a bad pump.

 

That lurch is the supercharger clutch disengaging. The HP that was being used to spin the supercharger is now used for forward propulsion, for a half second anyway. Your intercooler pump is almost certainly shot. Go ahead and replace it. Even if by the very remote chance the pump is not the problem, the pump will eventually fail anyway so there is nothing to lose by replacing it now. I'd go for the Johnson pump since it has a longer life expectancy than the current one. This will offset the the higher cost of the Johnson.

 

Brent

So I you are saying that I need to have my supercharger clutch check? And how do you go about doing something like that. I have never messed with a s b before and would like some direction if it is possible?

Thanks,
Roky

 

what he is saying is that as the s/c heats up the pump is malfunctioning. when the pump goes out the s/c overheats and the magnetic clutch on the s/c pulley kicks out. thats the lurch you are feeling as you go from forced air induction (330 hp) to n/a (250 hp)

 

I've read that the lurch happens due to the increase in available power from the engine not spinning the supercharger. End result is the same - the lack of acceleration is enough to make one cry.

Rokypoky, there is a way to test the clutch by applying voltage and checking if the clutch activates or not, but I don't know the details. Your symptoms, however, are classic for a bad intercooler pump, so that's what I'd replace if I were you. Incidently, several years ago my car lost power and I immediately thought of the intercooler pump. Went to my dealer for warranty work and they found that the clutch assembly was bad. The supercharger and clutch are integrated in one unit so the dealership had to replace the supercharger along with the clutch. The complete assembly was $7,000 USD, fortunately paid for under warranty. The good news is that myself and one other forum member have had our supercharger assemblies replaced so the failure rate is exceeding low. As for the intercooler pump, I only know of one forum member who has gone over 50K miles without a pump failure. Most of us seem to suffer failures between 30K and 40K miles. Mine failed at 31K.

 

replacement of the s/c and pulley clutch are only dealer done. many have replsced the bad clutch with a c3 setup or used pulley for thousands less.
not sure why they assume the s/c has to be replaced

 

That's good to know if I ever have another clutch failure. I'm guessing that the dealers can't get a separate clutch assy from MB so have to order everything. But then, what do they care, as long as it's under warranty MB pays for it all anyway.