developed rod knock on new motor

[Adjuster]

For mine, I filled the Accusump, then plumbed it and mounted it. (And charged it so the gauge read 30psi.) Then before I started the motor, and before I opened the accusump, did the EFI fuse out crank for 10, then wait about 3 seconds, crank 10 seconds more, wait 3, then crank 10 secs, and it's showing pressure on the stock gauge, then put the fuse in, then turned on the accusump, watched the pressure gauge go up past 30psi, and started the motor..

Normal drill was turn the key on, click on the accusump, watch oil pressure go up, and then start engine. Should be minimal wear to bearings this way throughout the life of the motor. BTW, with the sump "empty" after the oil change, I set the pressure to just 5psi holding the piston "empty" of oil. You can hear the piston moving around in the sump too from time to time, so there are times obviously when the oil pressure drops and without one, it could be doing damage to my bearings/engine.

 

[suprahooked]

For mine, I filled the Accusump, then plumbed it and mounted it. Then before I started the motor, and before I opened the accusump, did the EFI fuse out crank for 10, then wait about 3 seconds, crank 10 seconds more, wait 3, then crank 10 secs, and it's showing pressure on the stock gauge, then put the fuse in, then turned on the accusump, watched the pressure gauge go up past 30psi, and started the motor..

Normal drill was turn the key on, click on the accusump, watch oil pressure go up, and then start engine. Should be minimal wear to bearings this way throughout the life of the motor.

Nice set up Adjuster, maybe someday i will get that kind of a set up .
But as you know these cars can drain the wallet fast.
I hope he cranked it first with the fuse out.
John

 

[cjsupra90]

Yes, it does seem that it is hooked up correctly just the wording can seem contradictive because I am referancing it as mounted in an RX-7 and my car alike and that is with the ports on the left hand side where his on upside down with the ports on the right hand side so top and bottom are opposite.

Just to clearify miss conceptiong for others, here is a labled drawing for referance.

 

[tte]

Wait, I am assuming that you are using a true relocation unit and not a sandwich plate adapter. If this is correct, the here is the correct hook up.

Out port on the engine block adapter to the in port on the filter hanger / adapter, then out port of the filter hanger / adapter to the top port of the cooler, then bottom / side port of the cooler back to the in port on the engine block adapter. Remember though, the lines on the cooler if backward will not make a differance except that the oil temp will not be as accurately controlled.

Mine is routed like this

If oil is less than 180 deg oil route is :
OUT engine ---IN Remote filter---OUT Remote filter ---IN 180 deg thermotat---OUT 180 deg Thermostat---IN Engine

If oil is above 180 deg, oil route is
OUT engine ---IN Remote filter---OUT Remote filter ---IN 180 deg thermotat---IN Oil Cooler---OUT Oil Cooler---IN Engine

Cheers,
Roy

 

[spoolint78]

cjsupra90
mine is exactly like the setup described in the picture.

in from the bottom fitting (i.e the oil thermostat is on the top)
than it fills up the tank, and out from the side fitting.

suprahooked

the lines were full at startup.
i drove it for almost 3000km.

before the knock developed, i think i had an ignition problem, because it was breaking up around 4000rpm.

For the last 1500km, the startup oil pressure was fine, but cruising and reving it, from 2500+ the oil pressure stayed the same on the stock gauge.

 

[spoolint78]

is it possible that the bearings were dry when i started it?
i don't see how its possible because i let the car sit over night than drove it the next morning like i would any car.

I did have an incident when my oil line leaked and i was on the highway and the gauge dropped right above the 0 line.
pulled over, towed it home, topped up the oil and fixed the leaked and it never knocked.
Roughly 1500km later when it developed rod knock, i started the car and heard the knock, then it went away when oil pressure built and it came to an idle.

if that is the case, wouldn't all the bearings go bad?
i mean it seemed to me the engine started, then a second later the rod knock went away, meaning the rod had positive pressure going to it.

so far, your help has been greatly appreciated guys.
keep it coming.

 

[quake]

is it possible that the bearings were dry when i started it?
i don't see how its possible because i let the car sit over night than drove it the next morning like i would any car.

I did have an incident when my oil line leaked and i was on the highway and the gauge dropped right above the 0 line.
pulled over, towed it home, topped up the oil and fixed the leaked and it never knocked.
Roughly 1500km later when it developed rod knock, i started the car and heard the knock, then it went away when oil pressure built and it came to an idle.

if that is the case, wouldn't all the bearings go bad?
i mean it seemed to me the engine started, then a second later the rod knock went away, meaning the rod had positive pressure going to it.

so far, your help has been greatly appreciated guys.
keep it coming.

make sure your engine guy gets the clearences correct, its not the cooler. Also verify the oil pressure at idle warm and at 3000 rpm per tsrm. Run an extra quart of oil check the main galleys for debris check the crank passages. Install an aftermarket oil press gague.

 

[IJ.]

Spool: In the 4000 has it ever ran low on Oil?

 

[jdub]

I did have an incident when my oil line leaked and i was on the highway and the gauge dropped right above the 0 line.
pulled over, towed it home, topped up the oil and fixed the leaked and it never knocked.
Roughly 1500km later when it developed rod knock, i started the car and heard the knock, then it went away when oil pressure built and it came to an idle.

How many quarts of oil did you have to add to get it back to full after this "incident"?

Once a bearing is damaged, it's damaged and only replacing it will provide a long term fix. When oil pressure builds inside the bearing, it provides hydrodynamic lubrication to prevent the bearing, rod, and crank journal surfaces from making contact. If the bearing is damaged at some point, wear will occur...how fast depends on the damage. Once the clearance opens up to the point oil flow/pressure can no longer be maintained to provide the hydrodynamic condition...you will get rod knock.

 

[cjsupra90]

most likely your whole problem stems from the oil leak incident.

The time line adds up perfectely.
Engine, roughly 3000km's, oil leak happens at roughly 1500km's and according to your first post you have had a low oil pressure problem for roughly the last 1500km's, so therefore the leak cause some damage and the resulted in low oil pressure for the last 1500km's, the low oil pressure then accelerated bearing wear which leads us to the rod bearing problem at hand.

________________________________________________________________

Side note about rod oiling and oil pressure for you'll to think about.

The rod bearings never see the pressure that the gauge is reading, they always see a lower pressure (not sure exactly, but my guess would be somewhere between 25 to 50% less). The due to the fact that the only way to supply oil to the rod bearings is through the crankshaft and the only way to do this is to feed the crank via the main bearings. Being that a protion of the oil is allowed to bleed off from the main bearings back to the pan, there is your lose of volume and therefore pressure availible to be supplied to the rod bearings. This is why bearing clearance is so important, especially the main bearing clearance (too much there equals that much less oil supply for the rods). The other important thing is to change oil frequently, any junk that gets past the filter always attacks the mains first and wears them out faster, increasing clearance there therefore decreasing oil supply to the rods...... Just some food for thought.......

 

[jdub]

The squirters are also a source for losing pressure...a controlled leak. They are suppose to function at ~40 psi...if one (or more) get stuck open, it can be a significant loss of pressure.

IMO, a better option vs changing oil frequently is to use excellent filtration. Addition of a by-pass filter to the stock full flow will achieve sub 10 micron particulate removal. Or, use one of the CM filters like Adjuster has. Even using a good full flow filter (assuming it's working correctly) you should not have to change a good syn oil at less than 5000 miles.

 

[IJ.]

Bingo!

I didn't see that but all a 7M needs is a momentary interuption in pressure to touch a bearing and that begins the cycle and RK isn't far away....

 

[tte]

Good read guys...
Goes to show how extremely important the bearing clearances and the whole oil lube system is.
Could you cost a new rebuild and lots of money n time.


Cheers,
Roy

 

[suprabad]

what were your clearances on the main/rod bearings and the camshaft?

This sounds more like the problem to me.

I think you may be barking up the wrong tree with the oil cooler theory.

It's very common for machine shops that don't do alot of tight tolerence turbo motors (or are just plain sloppy), to not get the clearances correct. Usually they set-up the bottom end way to loose resulting in exactly what you've described.

Time to break out the plastigauge.

 

[jdub]

My money is on when he had a leak and ran low on oil
Cooler had nothing to do with it.

 

[tte]

This sounds more like the problem to me.

I think you may be barking up the wrong tree with the oil cooler theory.

It's very common for machine shops that don't do alot of tight tolerence turbo motors (or are just plain sloppy), to not get the clearances correct. Usually they set-up the bottom end way to loose resulting in exactly what you've described.

Time to break out the plastigauge.

If they did get the clearances wrong, I am sure they would not admit it.
Your engine builder might have trying to trick you into convincing you that it was the oil cooler.

Cheers,
Roy

 

[spoolint78]

My money is on when he had a leak and ran low on oil
Cooler had nothing to do with it.

i think this is where it all started.


if the bearings clearances were out of whack, i'm sure i would have noticed it instantly.

the engine builder is pretty good.
he's put together 7m blocks, and one just dynoed 712rwhp in a auto tranny, so i think he knows what he's doing.


hopefully this time it will go better.

i'm gonna flush out the oil cooler and the lines.
how should i do this?

 

[tte]

i think this is where it all started.


if the bearings clearances were out of whack, i'm sure i would have noticed it instantly.

the engine builder is pretty good.
he's put together 7m blocks, and one just dynoed 712rwhp in a auto tranny, so i think he knows what he's doing.


hopefully this time it will go better.

i'm gonna flush out the oil cooler and the lines.
how should i do this?

Did he mod the stock tranny to handle that 712 rwhp or was he using another stock tranny?

Cheers,
Roy

 

[Nick M]

What exactly do you think a tight clearnace is, since people want to mention it? I get tired of reading BS.

 

[bountykilla0118]

What exactly do you think a tight clearnace is, since people want to mention it? I get tired of reading BS.

I guess its something that he thinks he could physically "feel" the difference ............