developed rod knock on new motor

[spoolint78]

Got a few questions that i need some input on.

my motor was recently built, ross pistons, eagle rods, federal mogul bearings etc.
now it developed a knock a couple of days ago, after roughly 3000 km.

Before it blew I noticed that when i reved the car when it was warm the oil pressure stayed at one spot, just below 2, even when i was driving.

now i already pulled the motor.
i was running the rx7 oil cooler with -8 lines.
they were pretty long.

my engine builder sugguested i go to a small oil cooler, because he feels that the rx7 oil cooler was too big, and i was loosing too much pressure.
Is this possible?

He mentioned that all the oil must go through the oil cooler, then back to the engine.
the oil cooler has to fill up, and the feed is on the bottom of the oil cooler, so it has to work its way up.
The oil cooler also has a built in thermostat.

I don't see why this was a problem.
I drove the car for roughly 3000km, and this just happened.
but through 1500 of those km, the gauge read just below 2 while cruising at 2500-3000 rpm

i'm thinking of switching to the b & m oil cooler because it is thinner.
any other suggestions?

Before the bearing spun, there was gunk under the oil cap, and the pvc system had that coolant taste in it.
perhaps the headgasket was leaking, and the coolant was mixing with the oil?

When i removed the head, there was no signs of leaking.
all the pistons were black, nothing shiney.
I did have a little puddle of coolant poor out of my dp though.
Perhaps it was the turbo?
Even my engine builder said the headgasket was sealing fine.
Where could it have leaked from?

I'm getting crank and rod checked, with new bearings, and shimming the pump.
Any suggestions on how much of a shim i should put in?
i was thinking around 6mm.

 

[Justin727]

Not sure about the rx7 oil cooler but this is sad news to hear. Man I hope all comes out well.

 

[IJ.]

I wouldn't blame the cooler....

 

[tte]

I just did a engine rebuilt all on my own. I am running a big oil cooler with -8 an lines and have no problems with rod knock. I am sure there are people who have done engine rebuilds and used RX7 oil coolers with no problems.

Could be the engine rebuild that caused the problem.

Cheers,
Roy

 

[LordLo]

Possible, my 5sfe got rod knock because the hg was leaking coolant.

 

[GrimJack]

It can't be the cooler. Oil isn't sent to the cooler until after the rest of the system sees a certain pressure, specifically to prevent this.

If your oil was contaminated, or low, or your oil pickup was starved during a long high G turn, this would happen.

 

[starscream5000]

That mechanic has NFI what he's talking about with the oil cooler.

You were licking your PCV system??? :ugh:

 

[jdub]

It wasn't the cooler...the thermostat sends oil back to the motor until the oil reaches ~180 deg F. Coolant in the oil will cause damage to the bearings though. Perhaps the HG allowed coolant to seep into the oil passages to the head, but sealed around the cylinders?

Were you using an adapter and NA stud that routed oil to the cooler, eliminating the stock filter head?

For most motors, a 4-5mm shim is plenty to increase pressure.

 

[spoolint78]

jdub

i eliminated the stock filter head.

My understanding of the oil cooler, is that all of the oil from the pump goes to the oilcooler, then threw the oil cooler back to the engine.
is this correct?

if your suggesting that the cooler must meet 180 degree's but the oil cooler thermostat, how does the cooler send back the oil until it reaches that temp?

 

[spoolint78]

tte, and pics of how your oil cooler is setup?
my feed is on the bottom, and the return is on the top.

perhaps it should be the other way?
i don't see how it would matter though.

 

[jdub]

Any oil thermostat (including the RX7 cooler) bypasses the cooler until the oil reaches a preset thermostat temp. The only difference on the RX7 cooler is the thermostat is built in...the oil does not flow through the finned part of the cooler until that temp is reached.

The hose routing is important...the oil adapter on the block has the feed on the outside fitting, the center fitting is the return to the motor. The feed should be routed to the "In" fitting on the RX7 cooler for the thermostat to work properly.

 

[spoolint78]

my feed goes to the rx7 oil cooler side fitting.

The oil thermostat is on the other side (out) and that goes back to my motor.

could it be the lines are backwards?
i still drove the car fine.

I asked adjuster, and this was the method he choose.

 

[spoolint78]

here is a pic of my oil cooler setup.
so if the temps aren;t at 180 the oil flows through the one endtank, and it fills up, and goes straight back to the motor?

and then when it opens up, it fills the whole oil cooler?

in the pic the bottom is my feed coming from the oil filter, and the top is where teh return is going to the motor.

 

[IJ.]

Spool: Describe your Oil system from the pump please?

 

[p5150]

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

 

[spoolint78]

i'm not sure of the clearances.
i will aks this time around.

IJ, it goes from the pump, then i believe it goes straight to the oil relocation out, to the oil filter, then to the feed on the bottom of the oil cooler, to the outlet of the oil cooler back to the motor.

 

[cjsupra90]

The way that the RX-7 cooler is soppost to be routed is out of the motor, into the top of the cooler, out of lower side port of the cooler and back to the motor.

The RX-7 cooler will flow in either direction with no problems, just if it is hooked up backwards, the temp control valve will no function as accurately. The RX-7 coolers always flow oil through the cooler tubes all the time regarless of temp. When the valve is open (i.e. cold oil) about half of the oil is allowed to bypass the cooler tubes through the open port and the other half is still sent through the cooler tubes. As the oil increases temp, the valve start to close and allows less and less oil to bypass.

from your last post, I think that your problem is in the relocation unit from what you said.

it goes from the pump, then i believe it goes straight to the oil relocation out, to the oil filter, then to the feed on the bottom of the oil cooler, to the outlet of the oil cooler back to the motor.

It should go from the pump to the IN on the relocation unit, from the OUT of the relocation unit to the top port of the cooler, then from the bottom / side port of the cooler back into the motor.

 

[cjsupra90]

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.

 

[Adjuster]

I'm pretty sure I have mine right. On a cold day, the "far" end tank is just barely warm, and the tank with the T-stat in it is quite hot. (Conversly, on hot days, the whole thing is very hot.)

IIRC, the oil goes IN opposite the large nut that retains the thermostat, and OUT on the side of the tank. (So, his is setup correctly if the oil is going into the bottem of his cooler, and out the side back to the motor.)

On my car, there is no spin on adapter plate. The block is plugged, and the place where the NA cooler adapter normally goes is tapped, and the oil comes straight out from the pump crossover hose there.

It then goes back into the main galley after being filtered and cooled. No oil pressure is one of a few problems.

1) Your oil pump drive shaft broke. (Not very common.)
2) Your bearings are shot, and oil pressure never builds up due to lack of flow restriction.
3) Low oil level? (The usual suspect, and cause of so many rod bearing failures.)

It only takes a few seconds of no oil pressure to wipe out the bearing on the 7M.

You also mentioned that the oil pressure was not very high for quite awhile. Could the builder have missed something? I wonder if you have an internal oil leak at a pump line somewhere. It's possible most of your oil is being lost before it is ever routed to the filter, cooler and back into your engine.

Just re-read your first post, and when your engine started to show low oil presure at 3000 rpm, that was a sign there was a problem for sure. The only time your engine is without oil is when you start it up, and when you change the oil. And unless you blow out the oil lines, cooler etc, you have oil in there, so it does not take very long to have the new oil pushed into your motor. (Mine has a pre-lube, so I do not get the start up wear, but I do get the the oil change wear as I use compressed air to blow the oil out of the lines, and I dump the accusump so only new oil is put back into the engine/oil system.)

I do not reccomend ever revving up your engine when you change the oil untill you see full oil pressure. You can also pull the EFI fuse, and crank the engine over for 3 ten second periods, and you should start to see oil pressure on the gauge, then put the EFI fuse back in, and start up the engine, and you should have oil pressure right away.

I don't know why your engine failed, but I don't think it's your cooler, or how long your lines are. (Heck, I have over 21 feet of AN10 line in my setup, and over 8 feet of AN4, plus the AN4 turbo feed that is 2 feet long.... Now, between the engine and the oil filter, and cooler back to motor, there is about 10 feet, plus the oil filter and the oil cooler. The rest runs back to the accusump in the rear hatch area.)

The 7MGTE oil pump does move quite a bit of oil. We looked at the gear size and height of a high pressure/flow SBC pump, and they are about the same size. I'm not sure how fast they are run from pump to pump, but if they are anywhere close, the 7MGTE pump should handle your system no problem at all.

Check your pump, and check your oil pump drive shaft for damage.

 

[suprahooked]

Did you fill the lines and cooler before your 1st start up?
I pull the efi fuse and cranked it first to fill the lines & cooler, when i did my build.