Chevy Impala SS Forum banner
21 - 36 of 36 Posts

· Registered
Joined
·
6,532 Posts
The LT1 being reverse flow motor where heads are cooled 1st with water coming out of radiator so the head temp reading "may" be lower than what it is at WP.....IDK.

It is common knowledge that on a standard flow SBC the head temp reading was always hotter than the WP or intake manifold port which were used for the "idiot" dash light

IMHO since a B Body, at least the SS, has a temp "gauge" vs light so the sender is specific to a gauge, not just on at X temp like a sender would be for a dash light only.

Unlike 1st gen SBC where their water pumps have a NPT port or aftermarket T stat housing with a NPT port a temp sender could be installed, the Gen 2 LT1 does not have those. Inline heater hose sensor port would be an option if one could not remove the head plug for gauge sensor
 

· Registered
Joined
·
2,950 Posts
The LT1 being reverse flow motor where heads are cooled 1st with water coming out of radiator, so the head temp reading "may" be lower than what it is at WP ... IDK.
It is common knowledge that on a standard flow SBC the head temp reading was always hotter than the WP or intake manifold port which were used for the "idiot" dash light.
IMHO since a B Body, at least the SS, has a temp "gauge" vs light so the sender is specific to a gauge, not just on at X temp like a sender would be for a dash light only.
Unlike 1st gen SBC where their water pumps have a NPT port or aftermarket T stat housing with a NPT port a temp sender could be installed, the Gen 2 LT1 does not have those.
Inline heater hose sensor port would be an option if one could not remove the head plug for gauge sensor.
Before going on, note that Fleetwoods lack a dash temp gauge; they only get a light that lights up when the head temp is getting dangerously / too close to overheating. Don't know about RoadMasters.

So long as coolant flow and airflow are not compromised:
1. at idle and in metro / urban driving, the head temp sender & dash gauge tend to read hotter than the H2Opump temp sensor, as the cooling fan(s) airflow cools the H2Opump far more than the head temp sender which is also warmed by the exhaust
2. at light load and in roughly steady cruising, where the H2Opump is most efficient AND natural headwind basically makes fans superfluous, the H2Opump temp sensor and the head temp sender are basically closest to agreement.
3. at heavier loads and over 2750RpM, the heads (and exhaust) are making more heat as the H2Opump approaches cavitation

Mind, the above assumes everything's cool (pun works well here).

Once either airflow and/or coolant flow is in any way compromised, the head temp sender will always warn of excessive temps before the H2Opump temp sensor.
Hopefully Scott Mueller did not learn this from experience - I have.
 

· Registered
Joined
·
2,950 Posts
Take a look at this, for what it's worth:

Note that the LT1 H2Opump pumps LESS (gallons per min per horse) than the L98 H2Opump (with the L98's tstat open). This, on a more powerful higher compression engine.
To further clarify, the above chart references H2Opump RpM.
For the LT1, engine RpM * 1.269 = H2Opump RpM ... so 6000 H2Opump RpM = 4728 engine RpM
Over 4750 engine RpM, the LT1 H2Opump is not flowing any additional coolant, and may approach cavitation ...
 

· Registered
Joined
·
6,532 Posts
Yeah Marky, IDK what the non-performance B Body models had/have relative to gauge package so yeah with a "temp light" one is left to a when the F will the dash light come on (assuming it works) as with a gauge at least you can see temp rising...assuming one watches their gauges

Now to throw this into the mix of how RPM influences the efficiency of a mechanical.....vs the EWP which operates at a constant RPM...
 

· Registered
Joined
·
2,950 Posts
Yeah Marky, IDK what the non-performance B Body models had / have relative to gauge package, so yeah with a "temp light" one is left to a 'when the F will the dash light come on' (assuming it works), as with a gauge at least you can see temp rising ... assuming one watches their gauges ...

Now to throw this into the mix of how RPM influences the efficiency of a mechanical ... vs the EWP which operates at a constant RPM ...
1stly, the LT1 B- & D-cars are overweight performance models ... with, um, too much potential in OE form ...

2ndly, if memory serves, the Fleetwood's overtemp warning light gradually brightens (instead of just OFF-ON).
However, even assuming the driver's info cluster is CLEAN enough to see its initial faintly dim 'enlightenment' ...
How hot is that, EXACTLY? 'cause it's likely hotter than 235°F, already too close for comfort.
Caprices or RoadMasters (checked just now) warn much more gradually with a temp needle.
Fleetwoods pretend everything's just fine, until just before the schidt's about to hit the fan.

3rdly, we can revisit the electric H2Opumps much later ...
 

· Registered
Joined
·
1,200 Posts
Ok guys I need your help once more. My green wire to the gage in the dash for the temp is broken on the outside of the firewall. I just can't get to it where it is broken. So I want to slice it inside the car under the dash to run a new wire to my 3 wire plug in the water pump. I want to make sure I am getting the right green wire. Does that wire run throught the smaller white connector? A picture would be best.
 

· Registered
Joined
·
1,200 Posts
Thanks, that helps I was really looking for a camera picture. I still appraciate your guidance.
 

· Registered
Joined
·
1,200 Posts

· Registered
Joined
·
7 Posts
こんにちは。私の 95 カプリス ワゴンには、温度計が左端から 5mm ほど上がったり、動かなかったりすることもあります。これも断線の症状でしょうか?エアコンを切ると、温度計の針が動くことがありますが、また動きます。
 

· Registered
“91” Oldsmobile Custom Cruiser
Joined
·
401 Posts
こんにちは。私の 95 カプリス ワゴンには、温度計が左端から 5mm ほど上がったり、動かなかったりすることもあります。これも断線の症状でしょうか?エアコンを切ると、温度計の針が動くことがありますが、また動きます。
Hello. On my 95 Caprice wagon, the thermometer may go up about 5mm from the left edge or not move. Is this also a symptom of a disconnection? When the air conditioner is turned off, the thermometer needle may move, but it will move again.
TRANSLATION
 
21 - 36 of 36 Posts
Top