Hades12

What would happend if the two lines to the oil cooler were swapped?

rx7owner

isnt there 3?? now im curious...im gunna go look lol

Hades12

Fmoc.

Siraniko

iTrader: (13)

Top is inlet from front cover. if you have them switched, It wont circulate fast enough meaning, the tank has to be "FULL" for the oil to come out.

Hades12

Would it starve the engine and lock it down?

wecycle

It would cool the oil.

steve84GS TII

The FMOC always allows some oil to go through the core,to prevent stagnation and air pockets when your oil is cold and the cooler is bypassing.
If you hook the lines up backwards,itll still work,(meaning the cooler will flow and your engine wont blow) but the internal oil cooler thermostat will likely not appreciate the pressure pushing the wrong way on it.
It will most likely affect your oil cooling,but not your oil circulation once things get pressurized.....in other words,hook it up right....as Wacky indicated.

trochoid

iTrader: (6)

Just a guess here, without looking at the thermostat in the oil cooler, my bet is it would over cool the oil, i.e., bypass the thermostat by forcing it open all the time and not allowing the oil to warm up enough.

Even if the themo never opened up and you had no flow though the cooler, the oil pressure control valve will open and divert the oil through the engine. Not to be confused with the oil pressure regulator valve.

jayroc

I've heard that if you take out the thermo, the cooler will explode. I don't see how that is possible, but anyways..
Maybe they were referring to this oil press. control valve? Where is that located? Inside the front cover, right?
Not to jack your thread, but curious..

trochoid

iTrader: (6)

Tip for the day. Don't believe everything you hear, and use some common sense when you hear it.


So for a quick refresher:

1. There is a by-pass valve that opens at 149* f., located in the fmoc.

2. There is an oil pressure control vavle located in the front cover. This valve diverts oil to the engine and or the fmoc, varying in volume by temperature.

3. Oil pressure regulator, located on the rear iron. Oil pressure should be 64-79 lb/in at 3000 rpm and 12.8-38.4 at idle , or in D if automatic.

Siraniko

iTrader: (13)

There is a FMOC t-stat inside the large 24" nut. Like the radiator t-stat, it is there to warm up the oil (FC also have one behind the main pulley for the same purpose). Once warm, it will close the by-pass and will re-route the oil throughout the core. Without it, HOT oil will re-circulate back into the engine which MAY cause engine problem in the long run.

WackyRotary

Wackyracer, when you say the termo-pellet behind the main pulley on a FC, doesn't the FC oil coolers also have the thermostat built into the oil-cooler like a FB oil cooler?

Siraniko

iTrader: (13)

there are 2 in FC. IMHO, the thermowax idea is overkill considering that there is one in the cooler. To eliminate another source of failure, either shim it with M7 washers or replace with an ugraded version. I dot know how much it will cost. Shimming is what I do in customers cars and I dont use FC E-shaft in my own engines.

FB II

exactly, since the outlet will now be the top one it will need more force to circulate. someone get this man a

Hades12

So No way it would have caused the engine to Seize?

FB II

hard to say, how long was it like that?

Hades12

Till the engine quit turning.

Siraniko

iTrader: (13)

No lubrication will cause the engine to seize immediately as in a few minutes...talk to 79seven lol.

Insufficient lubrication will shorten the life of an engine. Like cancer...they will give you a time frame but...

Hades12

This one went about a mile down the road, <- what i was told.

jayroc

Knew I read that somewhere... Didn't you post on one of these threads trochoid?

https://www.rx7club.com/forum/showthread.php?p=259515
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/thurmo-valve-int-oil-cooler-410910/

Hades12, that's definitely suspicious if it quit after only a mile down the road, but oil still should have been able to flow around the thermostat even backwards I should think, at least when it's cold and the thermo is open. I am guessing the thermo shut like it's supposed to when it got to temp and the oil flow stopped. So, maybe the cooler only flows one way at temp?
It definitely wouldn't take long without oil..

wecycle

What part of this, if any, applies to my 1979 12A SA? To the 1983 12A I got from the JY for installation in my other 1979 SA?
Also what type and rating is needed for the hoses to/from the FMOC on a 12A SA?
Dennis L. Cote

trochoid

iTrader: (6)

The thermo vavle in the oil cooler works just like the thermostat in the cooling system, it's cold position is closed and hot position open to allow flow. If you gents look at the 85 FSM Sec2, p.3, you will see that when the thermo is closed, the oil pressure bypass valve allows the oil to flow through the engine, through the lower oil galley. You could take the cooler out of the system and block off both lines and the engine will still have the same amount of oil flow, hot oil, but oil none the less.

If this engine siezed up less than a mile down the road, there are many questions that need to be asked before assuming the cooler was at fault. How long was the engine running before hand? Old engine or fresh rebuild? If it was a fresh rebuild, what, if any thing was used for assembly lube?. You can actually run a fresh motor on assembly lube only, with no oil, for a short while. You won't like what you see when you tear it down but it will run for more than a mile. Was everything else assembled correctly? Ask me what happens when you forget to install the o-ring between the front cover and front iron. That motor had 6 hours of run time on it, with 0 oil pressure showing on the stock guage. It didn't sieze up but it went through all 4 bearings and scored the e-shaft. It did have some pressure though. The 2 qts. of Lucas I put in it all settled in the oil cooler, thought I would never get that goo out of it.

Jayroc, what I posted in my last post is directly from the FSM, that is the first time I have posted that data. I'm not sure which one of my posts you were refering to.

Wecycle, as for hoses, any hydraulic hose that has a temperature and pressure rating exceeding the oem requirements will suffice. I went over board on mine. They are rated at 2500 psi burst strength with a 600* temp ratng. Any thing rated over 500 psi and 300* will work. Keep in mind that the hose must be oil rated also.

Hades12

Thanks trochoid, that is what I thought but I wanted to get an answer with out leading the discussion.


The story is:

I bought a car and engine a few weeks ago, the engine was stripped down and bare. I sold it to a guy local. We spun it over by hand and it had good compression. He installed it in his car and it locked down about a 1mile down the road. He called and told my dad that he had hooked up the lines wrong and caused it and do I have another engine to sale him. I did not think that what he did would have caused the problem.

jayroc

I was talking about oil cooler bursting, but it's not really relevant so nevermind.

trochoid

iTrader: (6)

You can think about this several ways. When the engine is cold, the thermo valve is closed, the oil cooler has it's highest pressue up to that point, even if it does bypass a little oil when cold. The thermo valve is a restriction and the pressure in the cooler will be it at it's highest when the valve is closed, the oil is cold and the rpms are high. Where the valve is located, half of the cooler is always under a higher pressure than the other half when the valve is closed. Removing the valve reduces that restriction, hence the static pressure should be even through out the cooler, with no restriction to increase the pressure. The static pressure should never should never exceed the the relief pressure of the oil pressure regulator, unless the regulator fails and will not open.

Which is stronger, aluminum or rubber? If the oil pressure exceeds the designed operating parameters for the engine, the cooler should be the last part to fail. If the cooler hoses are in sound condition, the o-rings should fail before any other part, whether it be the o-rings around the dowel pins, the o-rings under the oil filter pedistal, the o-ring at the front cover, or the oil control o-rings. I think I listed them all. My best guess would be the oil control rings would fail, and lead to excessive exhaust smoke. The other most likely one would be the upper front dowel o-ring.

On my 12a-bp, I have the 85 psi opr. On the first cold start of the day my Autometer op gauge would go to 125 psi on 20-50w oil. Now that I have changed to 10-30w for the cooler weather, it hits 100 psi on cold starts.

This story of fmocs bursting, to me, is nonsense. The only way for this to happen is for the cooler to have structural fault before hand, and this is common with the 1st gen coolers. The bungs for the banjo bolts often crack, usually due to over tightening the banjo bolt by people trying to reuse crush washers. The bungs on the 2nd gen fmocs are much more robust and this is why I recommend them, instead of the 1st gen ones, when converting from the beehive.