Super Charger or Rod Noise???

ttabol

Registered User
Howdy All! My 93 SC is making a knocking noise at start up and once warm at around 1500RPM. The noise sounds almost like a rod knock but when you get under the hood sounds like it's coming from the top 1/2 of the motor or super charger. SC Fluid level is ok and so is oil. No obvious signs (no metal shavings burnt fluids or the like) by looking at the fluids either. Has anyone had this problem before or know if the SC can make this noise if it's going out? Can I test this by removing the SC belt....will the car still run enough to check? HELP!!!!!
 
Yup

Should run fine without the belt. Hope your knock goes away. Mine made all kinds of racket before I replaced it.
 
umm

Take off the belt and start it up, if it still knocks go get some rod bearings cause the last one on the passenger side is gonna let loose. Change them before they do your car in.

Have you blown a head gasket latly? seems like sometimes a rod bearing likes to go on the cylinder the head gasket had privously blown on, Im not sure if it's from the slight hydro lock or what, but I've seen it wnough times that I can say it's law lol.
 
slysc

When I spun a rod bearing. I could have sworn the sound came from my supercharger. In fact, it was making a squawk, squawk, squawk sound and I thought for sure my blower was toast. I had it towed home and I took my blower off and took it apart and checked everything. It all looked good so I put it back together and it still made the noise. So... then I took all the belts off and started the motor and it still made the noise. Thats when I knew it was a really expensive noise. Turns out I had a rod bearing spund and a main bearing spun and the rest of the rod bearings were in pretty bad shape. (150k miles).

So... given my experience, I would suspect you have a rod knock and it just sounds like it's coming from the blower.
 
Re: umm

Icemanmd said:
Have you blown a head gasket latly? seems like sometimes a rod bearing likes to go on the cylinder the head gasket had privously blown on, Im not sure if it's from the slight hydro lock or what, but I've seen it wnough times that I can say it's law lol.

It caused by coolant contamination of the oil. The coolant gets on the rod bearings and affects the top layer of metal. There are three layers. The bottom layer is the bearing shell which is steel. Overlaying that is a layer of copper and on top of that is a very soft metal alloy like lead-indium or other very soft metal.

The top layers job is both to serve as an absolute last ditch defense in the event of metal to metal contact but also to allow hard particles to embed themselves within itself and not scratch the crank. Anyway, coolant affects this embedable layer and it quite literally starts coming of the copper underlayment. Now its the engines enemy as metal debris and it'll do a real number on ALL the bearings. It is worth noting tha cam bearings are also covered in meatal that can be affected by coolant contamination. Personally, if you have an engine that has suffered coolant contamination of the oil, I fee it would be best to just yank it and install all new bearings. Unless you're getting ready to sell it :D (which BTW is the Number One excuse heard by mechanics when a customer is declining repairs. "Don't bother, I'm gonna sell it tomorrow". Then the car is back next year with the same customer and the same problem and he's bitching about how you didn't fix it the last time it was there and he didn't know why he came back to you.)
 
reply to parker

Parker Dean,
Might be the case in a small amount of cases, but being a Tech for ford then good year I have probably done a few hundred head gaskets over the years on many cars that had a real amount of oil contamination. I have also done sets on cougars and thunderbirds with no i'll effects to the bottom end. Of course they wernt run until the oil was white, if they were I wouldnt touch them. I have only seen the rod bearing head gasket connection on 4 cars all being supercoupes and all being the exact rod that the head gasket blew on. And all happening within 5000 miles of the head gasket repair. I would have to disagree with the babit contamination of the bearings from the very small amounts of water that does get into the oil pan. Usually when a supercoupe blows a head gasket it is a great blow out not seepage as in most cars and usually pumps the radiator dry pretty quickly. Since water doesnt compress and initally there is pressure in the radiator system I belive the first couple compression strokes with the cylinder full of water hydro locks it just enough that it sqeezes out the very small film of oil and allows metal to metal contact, which then whipes the babit off the tops of the bearing on the top bearing portion, to the copper. Which then not only allows alot of oil clearance, but as you say doesnt have a babit covering to to pick of the fine particles, which then cut up and score the crank shaft, which then does further damage. I think the volume of oil the the sc motor moves, covers this up a bit, and thats why it takes awhile to do it.
NOt to mention the idiot that keeps trying to start the car when it wont barly crank over because of the full cylinder of water. ANd him saying I just dont know I've changed the starter the solinoid and the battery and it just wont crank fast enough to start, all by the way it was blowing grey smoke out the exaust on the way home. Now I guarntee that whipes the babit off or flatens them very fast.


Does anyone else have, or seen this connection? I'm kinda interested. The next one I do I WILL do rode bearing immediatly and then write up what I find. My friend just bought a 90 with orginal head gaskets so I got a feeling I'll have a opertuninty any day now!LOL
 
Last edited:
NOt to mention the idiot that keeps trying to start the car when it wont barly crank over because of the full cylinder of water

D'OH! i did that on my 91 cougar when its hg went, got stuck in traffic and was panic cranking, later found out the motor had a spun bearing and had to replace the whole thing, :(
 
sorry dennis

LOL Maybe idiot was a bad word of choice I'll go with "Uninformed"

And theres number 1

Yes I have been guilty of it the first time I blew a head gasket on this thing I tried to start it. It was like it had a dead battery lol. I was like wtf! SO I figured it out when I tried to coast start it (there went my first SC rod)

I was in a walmart parking lot and it ran absolutly flawless. when I had shut it off. Never even dremt a head gasket was bad.
 
Re: reply to parker

Icemanmd said:
I would have to disagree with the babit contamination of the bearings from the very small amounts of water that does get into the oil pan.

What leads me to my conclusion is that every one that I can recall had the dark grey coloration of contamination instead of the bright silverish color they should have. Not saying your conclusion doesn't have merit or anything.
 
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