Strange Heat Issue

[BOBOCobra]

So I did a cam swap this winter and decided to just tear it all down and replace all rubber and rings and everything is awesome. I also decided to put on a Fitech EFI and I really like it. I had a mechanical gauge prior and left it in the hole by the water neck and put the Fitech sensor with fan control in the other port. there is a 30 degree difference. fitech is running 180, t-stat is 180, intake is 180+/- in various spots, mechanical gauge is 215. Only place the intake is hot is in the very front at the heater port. From heater port to bypass hose it is hot on the front only. Heater valve open, hoses are hot. Rad intake is 180/190. Head and intake gaskets correct. what's going on? Air pocket...?

[BOBOCobra]

Let me clarify that at ram air the mechanical gauge cools down to within 5 degrees of the Fitech but at idle it climbs. I have a secondary fan with probe in the rad set at 190 and it never comes on until Fitech sensor hits about 190+/-. Prior to rebuild the mech. gauge would run up to 200+/- and settle down to 180/185 after t-stat opened. Now it goes to 215 at idle and climbs until primary fan kicks on at 180 and it will stay at 210-215. All temps shot with infrared.

[jhv48]

I think you nailed it. Air pocket. Try more burping.

[trularin]

I noticed when I swapped cams ( went to .610 lift Mech ) my temps went up as I gained HP.

Have you considered an increase in HP as an adding factor?

Just my $.02 worth.

Tru

[BOBOCobra]

Thanks for the comments. Only real mod is WP bypass is plugged and I use the heater circuit for bypass.
Not a HP issue as I did not increase that much and its only the one side temp probe and its only a small area of intake that gets warm. ran it again last night and no hot spots on head. What I cant figure out is how it could push back towards the probe, yet the water neck is not hot, it should not do that, it will take path of least resistance and rad flow would be strange if it pushes backs into intake and not out through water neck. It has to be heater circuit related. Not using coolant after initial burp cycles (150 miles since then), no bubbles in overflow, not puking coolant, normal expansion and return to overflow bottle, no coolant smell in exhaust, 3 circ holes drilled in t-stat, .... i will keep trying to burp but any other ideas are welcome.

[cycleguy55]

Originally Posted by BOBOCobra

Thanks for the comments. Only real mod is WP bypass is plugged and I use the heater circuit for bypass.
Not a HP issue as I did not increase that much and its only the one side temp probe and its only a small area of intake that gets warm. ran it again last night and no hot spots on head. What I cant figure out is how it could push back towards the probe, yet the water neck is not hot, it should not do that, it will take path of least resistance and rad flow would be strange if it pushes backs into intake and not out through water neck. It has to be heater circuit related. Not using coolant after initial burp cycles (150 miles since then), no bubbles in overflow, not puking coolant, normal expansion and return to overflow bottle, no coolant smell in exhaust, 3 circ holes drilled in t-stat, .... i will keep trying to burp but any other ideas are welcome.

I'm curious as to why you plugged the intake / WP bypass. Ford put it there for a reason. It's a thermostat bypass and circulates coolant from the intake manifold to the water pump when the thermostat is closed. By plugging it you've cut off the flow and apparently created a hot spot, at least at idle. That hot spot likely disappears when you're driving it and the coolant flow increases.

[BOBOCobra]

I use the heat circuit as the bypass, heat valve is normally open and always circulates. Rather than going though WP bypass I route it out of the manifold through the heater core back to the rad and that's how I circulate prior to T-stat open. It gives me a little more flow and allows a nice even warm-up. Hoses on both sides of heater core are hot so I know its flowing. I also have 3-1/8" holes in t-stat for circ so no pressure can build should there be a problem and allows air to escape. There is plenty of bypass going on, no way this should create a hot spot, yet....that fitting area is exactly where it is hot, all the time, even if t-stat is open and full flow.

[cycleguy55]

Originally Posted by BOBOCobra

I use the heat circuit as the bypass, heat valve is normally open and always circulates. Rather than going though WP bypass I route it out of the manifold through the heater core back to the rad and that's how I circulate prior to T-stat open. It gives me a little more flow and allows a nice even warm-up. Hoses on both sides of heater core are hot so I know its flowing. I also have 3-1/8" holes in t-stat for circ so no pressure can build should there be a problem and allows air to escape. There is plenty of bypass going on, no way this should create a hot spot, yet....that fitting area is exactly where it is hot, all the time, even if t-stat is open and full flow.

"allows a nice even warm-up" - and yet you have a hot spot. The only thing you've changed was to plug the bypass and use the heater circuit. Coincidence?

If that were mine I'd re-install the bypass.

Just my $0.02.

[BOBOCobra]

Sorry, I should have clarified, I plugged that bypass over 4 years ago and I left it plugged after the rebuild. Heat issue is new. I was just splaneing how it is set up and did not clarify the timeline. It's easy to reattach and maybe I will give it a go, but that would be a strange turn of events. I have to say, outside of a stubborn air pocket it would be the only explanation. I'm going to swap probe locations and see what they tell me. Might be a bad mechanical gauge but they are usually pretty dead on.

[BOBOCobra]

Just to circle back and close this out, swapped probe locations, no change, burped a little, no change. Changed the Fitech probe and viola!!!! Bad sender, temps are running dead nuts. Glad I didn't tear out the intake!!!! What upsets me a bit is the Fitech controls my fans and they were kicking on 30 degrees late. I had set them up at 170 to be safe so it was actually almost 200. That sender was flat out wrong by almost 30 degrees.

[cycleguy55]

Originally Posted by BOBOCobra

Just to circle back and close this out, swapped probe locations, no change, burped a little, no change. Changed the Fitech probe and viola!!!! Bad sender, temps are running dead nuts. Glad I didn't tear out the intake!!!! What upsets me a bit is the Fitech controls my fans and they were kicking on 30 degrees late. I had set them up at 170 to be safe so it was actually almost 200. That sender was flat out wrong by almost 30 degrees.

Good to know you've solved the problem. Damn technology!

Enjoy the ride.

[spdbrake]

Glad your fixed up. And you probably already know this but the FITech temp sender has to installed dry w/no pipe dope or teflon tape.
The Thermal guns typically are not to be trusted on castings in determining internal water temps. They're great on hard lines though.
https://www.autometer.com/resources/...faq_view/id/11

[BOBOCobra]

Yep, the thermal gun gave me a false sense of security other than the one spot on the front of the intake, the mechanical gauge was right on the whole time, as expected. The hard heater line fitting showed high temps but that was it. Even the water neck and hose were low.

I agree on the sender, the Fitech manual says to tape it, I didn't and it sealed. The first one was not taped either, it is just a bad sender, honestly it looks like a low cost copy of the OEM model it uses. I use a very small dab of thread sealant, just enough to fill any gap that might open up since it is aluminum and brass.

Thanks for the feedback, I learned something about the thermal gun.