Haven't posted in a while but I've been out of the country for the last 14 months. I'm back for a couple of weeks and to my dismay, my supercharger is cutting out intermittently. Today I changed the pump out from the Johnson that I had previously (arguably) upgraded a few years back to a new Bosch pump, but no joy. The problem persists. It is definitely the supercharger cutting out because my boost gauge and power response are normal until power dumps and vacuum/boost flatlines to zero under throttle. It comes back and goes out intermittently while driving. Always works out of the gate but typically starts shutting off within 5 to 15 minutes, then may be off for a similar period, then back on, etc.

In replacing the pump today, I did not replace the coolant but I ran the pump manually on and off for several hours to purge air bubbles. I pinched the lines to do the exchange so I only dripped a few ounces that I recycled and topped off the rest. Coolant looks new, but has not been flushed in a while so I will plan to flush and replace, but I'll be really surprised if that cures the problem. Pump fuse checks OK. Someone in a similar post reported a fuse box issue, but I don't have a good feel for how to evaluate that. The car ('03 SLK32) is driven very little and has about 38K miles on it. Has factory SC pulley, but fully isolated cooling system with supercooler and separate reservoir. Other major mods are listed in my sig.

I am traveling back to Central America in two weeks, so I don't have a lot of time to tinker with it and would REALLY like full enjoyment from my car while I'm here, so any technical/troubleshooting suggestions are greatly appreciated.

 

if you didn't have this problem before you replaced the pump. ,,,two things you have the wires backwards
or the pump you installed is bad,,,when you check it did you SEE the flow ? how,where did u c the flow? my without being there to c the car i would say it is the pump, the pump only works (factory wired ) when the rpm is above either 1200 or 2000 can't remember which , as a test hot wire the pump direct to the batt and re test your car. because
you said supercharger is cutting out intermittently. only the pump does that,

 

Thanks, but I think you misunderstood -- I ordered and installed a new pump because the SC was cutting out intermittently, assuming that a new pump would cure the problem. It did not, and the car behaves the same way with the new pump. Note that I did hot wire the pump to purge air out of the circuit. It flows fine.

 

If you have an intercooler internal leak you can over temp the circuit. Are you seeing the coolant level drop a little? If it's a leaking intercooler you will be pumping air into the circuit while into heavy boost. Cruising around your car will be sipping the coolant. If the leak is serious you should be spraying coolant out of the reservoir cap ..... well, it depends on your reservoir and how long your boosting. Mine was a BMW power steering unit. Keep an eye on the level in the reservoir and look for signs of flash dried coolant. The other way to know is to pull one side of the manifolds and look for goo. Any at all and that's your problem. It does sound like intercooler circuit related. Lots of air in the circuit, bad pump, serious I/C leak are the most likely places to look first. Double check that pump just in case.

Les

 

Electrical plug at the magnet may be corroded or damaged wires. We have had bad contacts at the magnet before.

 

Les -- thanks for the good info. My separate intercooler circuit was a little low but I honestly can't remember the last time I checked it. I can see return flow into the reservoir nicely with the new pump. For an intercooler leak symptom, can I just check the y-pipe for goo without breaking the plenum gaskets? It's been a while but I want to recall that it can be removed separately. Or is it too high velocity through there for the goo to register regardless?

OneHundred80 -- I will evaluate the connection, thanks. I infer that you mean the connection behind the clutch and not just the exposed electrical connector on top (?)

Thanks again for the input!

 

I don't know if that's possible or not. If you manage you'll see goo in the Y.
The only time I lost my supercharger was on a race track after several laps at WOT with an intercooler leak and remote reservoir. In other words, I was really beating on it. It never happened to me driving on the street. Under what driving conditions is yours shutting down?

Les

 

Les -- It's cutting out under normal driving...no thrashing...

 

In my opinion, the only thing that would cause your intermittent symptoms is having the intercooler's coolant temperatures get too high triggering the sensor to shut down the electromagnet disengaging the supercharger pulley.

 

Thanks for the input. Certainly seems to be the consensus and my symptoms are consistent with high IAT. Curious though whether the sensor itself is ever faulty...(?)

 

They go out occasionally, or Rob probably wouldn't carry those at Needswings. He has them listed for $27.95, if that is what you end up needing. For that price, I bought one a while back as a backup.

 

I had this problem and it was moisture in the sensor junction. Dielectric grease ithe trick.

 

Thanks to everyone for the valuable input. I removed the y-pipe this morning (yes it is relatively easy without plenum removal) and it's obvious I have a significant intercooler leak. I'll update this post as I make further progress, but lead time on the upgraded intercooler may make it impossible for me to complete repairs before I leave the states again...

 

Nasty! Mine was a minor leak compared to yours.

Les

 

That is exactly the green slime color I had in a set of NW's intake manifolds that I bought second hand. He didn't even bother cleaning them for the sale. The bright side is that you'll be getting the new improved Rudy/Speedriven built IC, yes?

 

Yes indeed. Order placed today.

 

Yeah, pretty gross. But on the bright side I see a nice topographic image of laminar flow...

 

Color me green with envy. I recently had my SC and IC off and apart for cleaning, inspection, and to add the tweaked and coated SC snout and valve covers that I've been sitting on for awhile. Anyway, when It was off, I pressure tested to 25psi for several hours, and it passed. I was almost hoping that it would fail so that I could get the upgraded IC. If price wasn't an object, I would have swapped it right then,even though it passed the test.

 

Well unfortunately Rudy won't be able to have the replacement intercooler ready in time before I leave the states, so I will update this post in a couple of months when I get back and (hopefully) have all the parts to do the repair. Thanks again for all the input.

/C

 

Leave it at my house and I'll fix it for you...lol. Already replaced a leaking unit for one of Rudy's improved units. You can just leave the Wavetrac in the trunk!