cooling woes

BullittAndy · Jun 23, 2007

91 LX Hatch with a 306, AFR 165's moderate cam, ported intake.

Cooling system specs
-S blade 3300 cfm electric fan (pulling)
-stock water pump, stock pulley
-underdrive crank pulley
-Mr. Gasket 180 degree thermostat
-Water wetter
-New 3 row brass Radiator off ebay
-Air dam properly installed

1.First of all, can I trust the stock gauge?

2. If I can't trust it, how do I verify temp? Can I trust a cheap aftermarket gauge?

3. How hot is too hot? It reads 230 degrees at the hottest (bumper to bumper 95 degrees ambient)

Its not a airflow problem as it doesn't cool down on the highway. I also just put the stock water pump pulley back on with no change.

I'm thinking radiator but its a 3 row and brand new, how do you upgrade from a 3 row?

Thanks

HISSIN50 · Jun 23, 2007

1. No.
2. Cheap aftermarket mech gauges have worked ok for me in the past. YMMV.
3. 230*F is rediculous, especially with alum heads.
You really need to see accurate temps before you infer too much. I have used a throw-away candy thermometer from wallymart (99 cents) to check temps in the top of the radiator. If anyone does this, just be VERY CAREFUL of scalding-hot coolant splashing out of the radiator. Stuffing a clean shop rag around the thermometer and neck might not be a bad idea.

Also, they do make caps with thermometers in them (about 30 bucks).

You could try to infer ECT temps, but that can be misleading sometimes.

To get an idea about the radiator, you can use an IR thermometer to check inlet vs outlet temps. There should be a noticable difference.

Good luck.

BullittAndy · Jun 24, 2007

Panicked for nothing. I bought a cheap mechanical gauge from Autozone for $18 and installed it verify and temp never went over 195 degrees (fan themostat setting). I just taped the gauge in the grill and drove around.

I also bought a new temp sending unit and installed it. Guess what?

Yep, the sending unit was bad and the bonus is that my stock gauge is accurate (at least between 160 and 195 degrees)

What tripped me up was the apparently normal slow sweep of the gauge, I assumed that bad sending units either work or don't but they can also apparently read too hot, or do anything they want.

Tip-for anybody running too hot even with new cooling equipment, check temp, but if lazy change the sending unit, $5 and very easy.

Thanks Stangnet!!

1991vert · Jun 24, 2007

get an accurate gauge first, as suggested

HISSIN50 · Jun 24, 2007

Glad to hear you got it. FWIW, my stock gauge read the other way. They're just too useless/hysteretic/inaccurate/lacking calibration for deduce anything from.

sivart · Jun 24, 2007

where is the sending unit located?

HISSIN50 · Jun 24, 2007

sivart said:
where is the sending unit located?

On the lower intake behind the distributor. It has one wire going to it.
A new one from CSK set me back $4.19 some years back.

Good luck.

cooling woes

BullittAndy

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HISSIN50

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