IMPORTANT question — Crankshaft Rear Main Seal TagsNone

[NIsaacs]

My '01 service manual says: 80 in lbs.

 

[seafish]

Yup…THANKS.… that more or less correlates with what I think I found online … 89 in lbs or approx 7 ft lbs.

Definitely less then the 15 ft lbs that I was estimating
Gonna give it a go now and report back later.

 

[AH64ID]

What temp thermostat is in the Fleece Bypass?

 

[seafish]

@AH64ID the Fleece bypass thermostat is rated at 180* … I surmise it is meant to start opening a little sooner then the OEM 190* in order to promote more even flow from back (hottest) to front (coolest) part of the block.

 

[seafish]

@NIsaacs

can you tell me on what page # you found that in the FSM ??

 

[AH64ID]

@AH64ID the Fleece bypass thermostat is rated at 180* … I surmise it is meant to start opening a little sooner then the OEM 190* in order to promote more even flow from back (hottest) to front (coolest) part of the block.

Personally I wouldn’t want that for towing. Knowing how the fan is programmed I’d want a 210° thermostat in it to ensure proper operation of the fan and OE thermostat when towing.

Not sure what options there are, but I recall it being a SBC thermostat.

 

[NIsaacs]

@NIsaacs

can you tell me on what page # you found that in the FSM ??

9-279 bottom right

 

[seafish]

More progress…

New Cummins rear main seal started with the plastic install sleeve and also the depth/set tool that comes with the Mahle kit (which Genos does sell)

Even though I bought the Mahle kit which includes the rear main seal, install tool and also retainer housing gasket, I also separately bought a genuine Cummins rear seal which is what I actually on the truck, installed using the Mahle kit.

NOTE — I also bought and installed the genuine Cummins camshaft to adapter plate "square cut" O ring seal. This o ring is placed in a machined groove on the FRONT of the transmission adapter plate just where the camshaft ends at the rear of the block. That is just under the yellow protective cap you can see in the first couple of pictures.

Flywheel bolts and lotsa washers to finish pressing in the rear main seal evenly —

Rear main seal fully installed —

Starter and transmission adapter plate torqued back in place --

 

[seafish]

Personally I wouldn’t want that for towing. Knowing how the fan is programmed I’d want a 210° thermostat in it to ensure proper operation of the fan and OE thermostat when towing.

Not sure what options there are, but I recall it being a SBC thermostat.

Not sure what the problem is … the bypass thermostat starts opening at 180 but the OEM thermostat that it ties into doesn;t open until 190, so as far as I can tell, it just promotes flow through the block until the main thermostat opens at the factory specified temp.

At that point, they are both circulating thorough the radiator as well, which is still cooled/controlled by the ECM/fan.

What am I missing??

 

[AH64ID]

Not sure what the problem is … the bypass thermostat starts opening at 180 but the OEM thermostat that it ties into doesn;t open until 190, so as far as I can tell, it just promotes flow through the block until the main thermostat opens at the factory specified temp.

At that point, they are both circulating thorough the radiator as well, which is still cooled/controlled by the ECM/fan.

What am I missing??

The issue is occurs when you end up running cooler than the OEM 190° thermostat would have you running, so the fan won’t cycle like it should while towing unless you’re making a lot of heat.

Under light loads only the rear thermostat will be open, which means you’ll run cooler and reduce efficiency too.

The 180° thermostat is better for race applications, but for towing you want the main thermostat to be the primary regulator of the engine temp, not the secondary.

 

[seafish]

The issue is occurs when you end up running cooler than the OEM 190° thermostat would have you running, so the fan won’t cycle like it should while towing unless you’re making a lot of heat.

John, I'm probably just being thick headed and am NOT trying to be contradictory … but since the main thermostat is NOT opening yet (until 190), isnt the rear themostat being open at 180 just promoting a more even heat distribution between the cylinders and NOT cooling down overall temps, even at lower loads ??

 

[AH64ID]

John, I'm probably just being thick headed and am NOT trying to be contradictory … but since the main thermostat is NOT opening yet (until 190), isnt the rear themostat being open at 180 just promoting a more even heat distribution between the cylinders and NOT cooling down overall temps, even at lower loads ??

Under lighter loads the rear thermostat will be the only one opening, meaning you’ll run 180° until you have a need for more power and heat rejection.

 

[seafish]

But the rear bypass thermostat only connects to a riser ABOVE the OEM thermostat which is remaining closed until 190…doesn't that mean the bypass thermostat is just recirculating coolant in the block until the OEM thermostat actually opens ???

Maybe thats what I am unclear on..the direction of coolant flow.

 

[AH64ID]

But the rear bypass thermostat only connects to a riser ABOVE the OEM thermostat which is remaining closed until 190…doesn't that mean the bypass thermostat is just recirculating coolant in the block until the OEM thermostat actually opens ???

Maybe thats what I am unclear on..the direction of coolant flow.

That’s the outlet for the bypass thermostat, which allows it to dump into the radiator.

When the coolant at cylinder 6 reaches 180° the bypass thermostat will open and likely under most empty driving keep the truck below the normal 190° operating temp.

 

[seafish]

Ah ha …in my head I had the flow going the other way

 

[seafish]

 

[Regcabguy]

Mine seeped at 37K. You did well. We both live close to the coast but your oil pan looks much better than mine.

 

[seafish]

We both live close to the coast but your oil pan looks much better than mine

What bothers me is that —

1) the clear coat on the oil pan has been peeling off in sheets for 10 years now

2) there is a fair bit of surface rust on the bottom of the oil pan, which I will now take the time to prep and paint

3) as I was tightening up the four bolts on the back of the pan to the seal retainer housing, a bit of gasket pushed out and broke off from around one of the bolts and wanted to do the same on another one…I am hoping that the RTV that I also used will keep it sealed … guess time will tell.

 

[seafish]

The issue is occurs when you end up running cooler than the OEM 190° thermostat would have you running, so the fan won’t cycle like it should while towing unless you’re making a lot of heat.

Under light loads only the rear thermostat will be open, which means you’ll run cooler and reduce efficiency too.

The 180° thermostat is better for race applications, but for towing you want the main thermostat to be the primary regulator of the engine temp, not the secondary.

@AH64ID

Been too busy in the wood shop to make much progress on the truck

That said, after work today, and based on what AH64ID would do if it was HIS truck , I went to Napa and bought and installed a NAPA/Balkamp premium thermostat for a small block chevy 5.7 hemi that is rated at 195* and put that into the Fleece Coolant bypass …so now both the Fleece and the OEM thermostat will be opening more or less at the same time, with Fleece starting to open just a tad later.

The 1x4 fir that you can barely see under the thermostat is a "nickel gap" T&G for a client's ceiling.

 

[seafish]

Ran 4000' of it today by myself …ended up walking over 10 miles in the woodshop !!!