OK another dumb question because I just want to understand but I don't. :-) Some of you might remember I thought I had a head gasket issue but they pulled the heads and there wasn't. The mechanic had thought the coolant was building pressure because of the deadhead in the heads.

They installed a coolant return which routes the coolant from the back of the head up the the thermostat housing. The other coolant route change that was done is from the oil cooler to the degas bottle because I had a ported intake installed also which doesn't have coolant routing. Also the egr cooler is now physically removed and coolant is not longer flowing through it. I had hoped to route the coolant to the return line under the degas bottle but they routed it to the degas bottle and stepped down the 3/4 ID hose to whatever fits on the degas (1/4 maybe?).

Anyway, so now my coolant stays at 192-194 under almost all conditions. I ran a hot tune through the mountains when it was 80 degrees and pushed it hard and coolant would not go above 194. However, my delta has increased, even under no load. It's 10-12 degrees under cruising speed and up to 20 so far when pushed hard.

I don't think my oil cooler is clogging for a number of reasons. I'm thinking the coolant routing changes increased the delta. Not sure it's such a bad thing but looking for opinions. Is it decreased flow through the oil cooler because of the stepped down hose size into the degas bottle? Or could it be the coolant return is just keeping the coolant that much cooler and the oil is running the same temp it would have under that same conditions stock? Does it matter that my delta is high without the egr cooler and my coolant is staying so cool?

 

I'm not familiar with the stock routing, but assuming it does not step down like your setup does, I'd consider that the issue. Pressure drop is related to change in diameter squared. If there's appreciable pressure drop, the step down, even if it is short, can really add up. Water will take the path of least resistance and your routing appears to have added enough resistance to upset your oil cooler.

 

I think they would have been better to come from the oil cooler to the heater core and let it return to the degas that way. Or run it from the oil cooler to a new wye in the return after the heater core. The small hoses going into the degas (intake and radiator) were only to provide a small flow to burb out any trapped air.

 

Yeah I have the hose and a Y adapter to run it into the return after the heater core or under the degas bottle. I'll change it when I get a chance but not too worried about it right now. Especially with winter coming up here, I don't think my oil will get too warm :-) It only got to about 210-215 when I ran it hard through the mountains on a hot day. So you agree that it increased the delta by restricting the flow?

 

My guess is that it is, you're not removing as much heat energy out of the oil that you could due to low flow. And agree you're not that elevated and you do monitor so you'll have your own warning system when you think it gets too funky.

 

 

Good to hear that akblackfoot! Would you say the driven diesel coolant return made the biggest difference in your coolant pressure and temps?

 

Yes, for sure. After the coolant return install pressure dropped significantly but the other benefit I noticed is that coolant temps stay lower also. I haven't towed heavy with it since the install but I've run it hard through the mountains on a warm day and coolant temp stays at 192-194. What I just did wasn't related to the coolant return but with the coolant reroute since the ported intake doesn't have a coolant path like the stock intake.

 

Sorry for highjacking the thread just had to ask. Someone here recommended me to read through one of your threads and the hot spot/dead spot in the back of the heads just made complete sense to me so I went with the return system vs oringed heads. If this fails, oringed heads it is for me but my truck seems to run cooler although haven't tested the coolant pressure. Thanks for sharing.

 

Yeah definitely runs cooler. I couldn't get coolant to rise above the t stat setting running a hot tune up through the mountains on a warm day. I don't think I've seen 200 degree coolant since the install. Seems to be multiple added benefits of the coolant return system but it's not a very popular mod. If somebody is having head work done I think it's a no brainer to do it. Reading some information and threads online I came across some saying coolant wouldn't get up to temp in the winter but I didn't experience this at all in temps as low a -25F this past winter.

 

Thanks for the thread!