Getting hot on freeway but stays cool at stop/low speed??

[04OWwhipple]

Just wanting some feedback on ECT temps that others are seeing. To make it short, I replaced my engine due to cracked block and now it seems to run hotter than I recall.

Radiator has be professionally checked and cooling system has been thoroughly flushed. Reische 170 t-stat and fluidyne radiator. Car runs 176 at a stop all day long. Start driving on the freeway (6th gear roughly 2200-2500 RPM) and temps will slowly increase to about 200 and sometimes higher. It was 87 degrees on my way home from work today. Get off freeway and temps start to come down in stop and go.


What does your car run at and does your temps rise at freeway speeds?

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[MG0h3]

I just dropped down to a 170 from that factory stat.

Sits around 176 idling as well.

If I rip on it a bit it’ll creep to upper 180s but hovers around 185 cruising around now.

You’re car will generate more heat moving, but the extra air flow over the radiator should help mitigate that.

If you’re sure there isn’t air in the system (this doesn’t sound like it) I wonder if the water pump is weak.


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[04OWwhipple]

I just dropped down to a 170 from that factory stat.

Sits around 176 idling as well.

If I rip on it a bit it’ll creep to upper 180s but hovers around 185 cruising around now.

You’re car will generate more heat moving, but the extra air flow over the radiator should help mitigate that.

If you’re sure there isn’t air in the system (this doesn’t sound like it) I wonder if the water pump is weak.


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I have thoroughly bled the system multiple times so I no there is no air pockets in it. Before engine replacement my temps were basically the same as what you are seeing. Would see 180s sometime into 190s when really beating on it.

I did replace my OEM water pump with another fresh OEM pump when reassembling the engine and have thought about going to a high flow pump to see if that resolves it getting so warm while just cruising.

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[Fastback]

How many miles on the new engine? New motors tend to run a little hotter on a rebuild, any motor. Once everything has time to seat, temps cool slightly. With that being said, your temps do not seem abnormal.

 

[04OWwhipple]

How many miles on the new engine? New motors tend to run a little hotter on a rebuild, any motor. Once everything has time to seat, temps cool slightly. With that being said, your temps do not seem abnormal.

I'd have to look to be exact but somewhere around 1000-1500 miles.

These temps are also running full E85. About a month ago I was running pump and headed to refill with E85. It was 105 out and the ECT got up to 222 on the freeway. AC was off the entire drive. After getting E85, it ran about 213 on freeway headed back home. Probably about 15-20 min on freeway at speed each way to station.

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[98 svt]

I saw 212 on the highway after my rebuild and turbo install. I was still running the OEM radiator.
Put a 3 core Champion radiator in and now it doesn't even hit 190 very often.

 

[railroad]

If you have not replaced the lower radiator hose, check to see if is collapsing at sustained rpm.

You might be able to do this in the drive way.
Good luck,

 

[Rich'sTRsvt]

May want to check if your radiator isn’t blocked somewhere. When the car is hot the radiator should be pretty hot all over as well. If it has cold spots than it may not be working properly anymore.

 

[04OWwhipple]

May want to check if your radiator isn’t blocked somewhere. When the car is hot the radiator should be pretty hot all over as well. If it has cold spots than it may not be working properly anymore.

I might be trying that next, the problem doesn't present itself at idle and I will have to remove the fan to shoot a temp gun at the radiator and see if it stays consistent




I just replaced the OEM water pump with a stewart high flow unit and that didn't have any affect on temps.

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[geoffmt]

Air pocket? Or collapsing lower hose. By any chance is the fan new? Aftermarket? If so could if be reverse wired? That’s all the ideas I have


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[railroad]

At highway speeds the air flow should be sufficient to cool the engine, without the fan.
Air obstruction should not be an issue, or the it would not cool at idle.
The coolant flow is the issue, either through the radiator or passages to and from the radiator.
I guess no signs of a head gasket leak?

 

[98 svt]

1 more quick tip that works for many:
Make sure your air deflector is still intact. It's the black plastic piece below the radiator that deflects cool air up. Many times it has been removed/is missing.

 

[04OWwhipple]

Air pocket? Or collapsing lower hose. By any chance is the fan new? Aftermarket? If so could if be reverse wired? That’s all the ideas I have


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I have throughout bled the system, so I'm certain there are no air pockets. I have no check for any collapsed hose during these times that is gets hot. The fan is not new and has been on the car for years. It is also drawing air correctly

At highway speeds the air flow should be sufficient to cool the engine, without the fan.
Air obstruction should not be an issue, or the it would not cool at idle.
The coolant flow is the issue, either through the radiator or passages to and from the radiator.
I guess no signs of a head gasket leak?

This is truly my concern. Being that this is a rebuilt replacement engine, I really hope that there is no passages in the block that are restricting flow this causing my temp issues.

1 more quick tip that works for many:
Make sure your air deflector is still intact. It's the black plastic piece below the radiator that deflects cool air up. Many times it has been removed/is missing.

I did make sure that the air deflector is still intact and in place.

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[geoffmt]

I’m very curious to learn what you find out


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[Lambeau]

Exhaust restriction?

 

[04OWwhipple]

Exhaust restriction?

I don't think so but haven't measured that, the car has smooth power delivery and nothing erratic shows on dyno pulls. Long tube headers with 2.5 inch exhaust all the way out.

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[04OWwhipple]

UPDATE: I was driving home from dinner on Friday night and the car started to over heat between light on the way to highway. Pulled over and had no fan. Wiggled the fan connector and the fan came on. So I need to replace the fan connector and see what happens. Thinking maybe I haven't had full fan speed for awhile now due to the burnt connector.

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[01yellercobra]

The fan will affect low speed cooling. But it shouldn't be an issue at freeway speeds.

 

[03cobra#694]

My thought as well.

 

[04OWwhipple]

The fan will affect low speed cooling. But it shouldn't be an issue at freeway speeds.

I would tend to agree and after putting the engine back in and getting the base time set up in my Haltech turning the fan off at high speed, the car actually runs even warmer. Which is also abnormal

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