Cab heater

[MrMikey4026]

Mine was there, but the bypass blocker had fallen off.
You might want too have a look, cant get any heat if you cant warm up the engine.

 

[coachgeo]

Mine was there, but the bypass blocker had fallen off.
....

can you elaborate on this?

 

[Ronmar]

can you elaborate on this?

Its a 2 plate thermostat. The upper port to the rad is closed when cold and the lower bypass port is open to recirc coolant back thru the engine(or thru the trans cooler on the A0).

As the engine warms and the thermostat opens, the core shifts the 2 plates down, opening the passage to the rad and closing the bypass passage.

If the bypass was blocked it would still warm up, and you would have plenty of flow thru the heater and the hose to the expansion tank which both return to the water pump the same way the bypass was intended to…

if the bypass plate was missing/not blocking its port well it would warm up like normal except it might not cool as well as it would always be mixing in/diluting or reducing rad flow…

lots of engines used non bypass cooling systems, but the bypass is better for a more stable temp as it mixes in the cold coolant from the rad instead of just injecting it straight to the block as the thermostat cycles open and closed.

 

[tennmogger]

Some, if not all, LMTV have a restrictor in the input of the transmission cooler to greatly reduce the flow through the trans cooler. The restriction is a machined cylinder that slides into the tube of the cooler and the left radiator hose fits over. There is a hole in the restrictor, maybe 3/8 inch dia. The restrictor would reduce warmup time so if your truck does not have it, warmup would take longer. I don't recall this ever being mentioned on the forum but I have seen the restrictor in 3 trucks.

 

[Ronmar]

Some, if not all, LMTV have a restrictor in the input of the transmission cooler to greatly reduce the flow through the trans cooler. The restriction is a machined cylinder that slides into the tube of the cooler and the left radiator hose fits over. There is a hole in the restrictor, maybe 3/8 inch dia. The restrictor would reduce warmup time so if your truck does not have it, warmup would take longer. I don't recall this ever being mentioned on the forum but I have seen the restrictor in 3 trucks.

oh yea there is a restrictor there where the bypass line connects to the port on top of the trans heat exchanger. Even in place it has enough flow to keep the engine from warming until it gets load applied. At 65f in gear at slightly elevated idle(cold wx warmup procedure), my thermostat will not open until I put in an exhaust restrictor or drive it to add more load…

it is a lovely machined restrictor I did a little machine work to it, welded a fitting to the top over the center hole and welded it into place in that top port on the trans heat exchanger. I re-routed my heater return line down to this new fitting/port when I de-installed that bypass pipe and re-routed the bypass flow back into the water pump and block as Cat intended…. Warms up much nicer now…

 

[INFChief]

Took the Warrior Wagon out for an ice cream run yesterday. My wife drove. She enjoyed it!

Meant to post an update on the operating temp in the post about getting it registration & inspected. Temp gauge works and the heater is hotter than a Detroit pistol. Apparently this rascally wabbit needs to run on the road to get up to operating temperature. Unlike a girl I once knew she won’t get hot just idling.

 

[Ronmar]

Took the Warrior Wagon out for an ice cream run yesterday. My wife drove. She enjoyed it!

Meant to post an update on the operating temp in the post about getting it registration & inspected. Temp gauge works and the heater is hotter than a Detroit pistol. Apparently this rascally wabbit needs to run on the road to get up to operating temperature. Unlike a girl I once knew she won’t get hot just idling.

Yep, with the bypass flow going to the trans cooler/heat exchanger, the A0 will not warm up until the trans warms up and until enough load is applied to overcome the cooling capacity of the transmission. With my altered flow, mine warms right up to op temp now unless I have the heater flow on…

 

[TomTime]

Yep, with the bypass flow going to the trans cooler/heat exchanger, the A0 will not warm up until the trans warms up and until enough load is applied to overcome the cooling capacity of the transmission. With my altered flow, mine warms right up to op temp now unless I have the heater flow on…

But his is a A1 like mine is...is it the same?

 

[INFChief]

Yep, with the bypass flow going to the trans cooler/heat exchanger, the A0 will not warm up until the trans warms up and until enough load is applied to overcome the cooling capacity of the transmission. With my altered flow, mine warms right up to op temp now unless I have the heater flow on…
[/Q

Ronmar, could you shoot me a message with what you did & how? Much appreciated. Jeff

 

[Ronmar]

But his is a A1 like mine is...is it the same?

Oh, no, was thinking this was an A0 discussion. The A1/A1R with the cat 3126 and C7 did not divert the bypass coolant down to the trans cooler…

 

[TomTime]

Oh, no, was thinking this was an A0 discussion. The A1/A1R with the cat 3126 and C7 did not divert the bypass coolant down to the trans cooler…

Thanks very much for the clarification. One less thing to have to worry about.