valve seat drop - Parso post
 

Hi Parso, wow, not nice. The dread of the hemi owners. Did motor overheat? What is km on motor?
I changed the thermostat on my motor from the to a 90 degree plus changed the fan activation temp to active at 95 degree.

Yeah scary to hear about one so close to home ay :(

I'm not convinced a lower thermostat and earlier fan activation will be much help, although I've still done it.

It's sounding like heads/seats overheating during the heat-soak period after shutdown. Even if we can keep the engine ~10C lower it might be a headstart, but localised temperature during heat-soak could still be excessive. The majority of that heat is being 'soaked' from the exhaust manifold and valves, which are much hotter than thermostat temperature.

In a well-engineered engine everything can handle the heat-soak and the cooling system can absorb the heat without too much boiling and causing hot spots. But the valve seats in the early hemis aren't retained, and if they're overheating that probably means the cooling system isn't able to get the heat away passively.

So I've pulled the trigger on a Davies Craig electric water pump combo. Plan is to plumb it inline with the mechanical pump to circulate coolant after shutdown, with a small pusher fan in front of the lower radiator. Bit of an experiment... it should work and help in theory lol.
Running a true aux pump on a bypass circuit like some OEMs would probably be a safer bet, but I like the idea of having some redundancy on the whole system... assuming either pump can circulate enough coolant if the other pump fails.

Hey mate,

Sorry for the slow reply, I don't check the forums all that often.

The motor had 208K on it and it has never overheated under my ownership. It certainly does run warm though. On the gauge it pretty much always sits bang on the middle, maybe a little past at times. The most i've ever seen the gauge go up to is maybe close to 3/4 across and that's generally under decent load, however the fan comes on full noise and it quickly zips back down.

That said my scangauge indicates that temperature is around 112c which does seem a bit warm, not in the realm of overheating but warmer than i'm comfortable with.

James I'm interested in how you find plumbing up an electric pump inline with the mechanical pump goes. I had considered doing the same however was worried of the resistance to flow that might present. I had instead considered running a small aux pump in the heater hose line instead which i would make a circuit for that would run for ~10 minutes after shutdown. That said i'm not sure if there is a valve that stops flow when the heater is off and also i'm not really sure of the coolant flow (anyone have a diagram for the hemi) hence i'm not sure my plan will work... yet.

I too have changed the fan activation temp via a superchips tuner however it seems to have had no effect.What did you use to change yours skala and does it work?

As far as from here, the engine is soon to get rebuilt. Just a stock rebuild nothing fancy but i'll be having the whole thing reconditioned and the heads will be getting completely freshened up too as well as new oversized valve seats in each cylinder to make sure it doesn't happen again! *touch wood*

I'm also taking the opportunity to change pretty much every hose and sensor in the engine bay, should hopefully be near as new when i'm done. I'll also be chucking in a dual core alloy radiator in, hopefully help the cooling system efficiency. Overall the wallet is going to hurt for a while!

Hi Parso. We used the HP Tuners to change the fan activation. Select PWM linear type fan control and then set the ECT for 95C. The fan which should always be spinning slowly, will then start up. I have set 100C for full speed.
My temp were also running like yours, but bit lower. I did not like it.
Like mentioned, I changed the thermostat to a 90C one.

Hrmmm I might have to look into HP Tuners or something similar. I was thinking about adding a relay on a thermostat like a few have done as described in the how to thread however If i can actually get the set points to change in the ECU that'd definitely be preferable!

I too am running a cooler thermostat (190f) however the temp is always above that so it'd be pretty much always open. The temptation to remove it during summer is high!

Removing it altogether will make it worse, the water flow is usually too high through the radiator to actually cool it

Sent from my SM-G930F using Aussie Jeep Offroad mobile app

That’s a myth.
It can sort-of be true in some scenarios with some setups where the higher flow and/or pressure causes turbulence or pushes coolant through a bypass or radiator overflow.
Lower pressure also lowers the RPM the pump cavitates, which also happens when RPM is too fast (if a mechanical pump is over-driven for example.).

But just circulating coolant faster doesn’t reduce cooling on its own, since there’s more “passes” so to speak.

@Parso, I lowered my fan temps using the Flashpaq too... I think it worked, but haven’t paid much attention to be honest. I wouldn’t hear the fan anyway over the baby screaming or our 3yo watch the iPad.

Received the EWP150 pump and controller from Davies Craig the other day, pump looks like a serious bit of kit! Still waiting for the fans (decided to use two 11” pushers in front of the condenser, below the trans cooler.) and thermoplastic clamps then I’ll rig it all up and do some experiments.

I’m interested to see if just running the fans alone without circulating will make any difference to the peak temps during heat-soak... that’d be a cheap and easy measure for other Hemi owners.
That seems to be good enough for our Volvo V8, which is a very compact and lean (aka hot.) engine.