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mrtazwrench wrote:

Blake wrote:All the hoses get 'warm' but not 'hot'. I think it has some air in the system...

I have 2 thoughts on this...

Is it plumbed to the heater as some older GM trucks were with one of the heater hoses to the radiator, those always had heating problems.

Also I had a 360 that would not warm up I found a bad impeller on the water pump.

It's a new water pump and yes, the heater hose goes from the engine to the heater core, then from the heater core to the radiator. My water pump has a fitting in there to run the heater hose too, but it's capped off.

Should I put the heater hose onto the water pump? That wouldn't be the stock way that Chevy did it..

mrtazwrench wrote:

Blake wrote:All the hoses get 'warm' but not 'hot'. I think it has some air in the system...

I have 2 thoughts on this...

Is it plumbed to the heater as some older GM trucks were with one of the heater hoses to the radiator, those always had heating problems.

Also I had a 360 that would not warm up I found a bad impeller on the water pump.

I am going through this with my Caddy swap. The stock set up went from the back of the head to the heater core to the rad. I need to see if I can find a water pump with the extra port for mine.

On yours, I would cap the rad and hook that hose to the pump.

I'm gonna hook it up to the water pump then...

Blake wrote:
I think that if my wife and I were to line up the 401 TBI waggy versus the 4.3 TBI J20, the J20 would win by a nose...

After putting about 400 miles on the J20/4.3L and then driving the 401 Waggy into work this morning, I have to change my stance.

The 401 in the waggy would smoke the 4.3L in the J20 in a race.

Yeah man, it is like having a V8.

fulsizjeep wrote:Yeah man, it is like having a V8.

And paying the gas of that big V8 $$$

I put 4 gallons of gas in it and drove 60 miles round trip to the junkyard. All interstate going 75mph +. Judging from the gas gauge, it burned pretty much exactly 4 gallons of gas on that trip.

So, give or take, It's getting 15mph (ish). Compared to to the TBI 401 in the waggy which get's 10MPG on that same trip.

You should be able to get close to that on the ole 401 though Blake. Phoebe peaked near 13 on our annual AZ trip in Nov.

Yeah, I dunno. Ethan hasn't been able to do it and he knows WAY more than I do about tuning the EFI. Last I heard, he is getting 11mpg out of his TBI 401 with a 727 auto tranny, stock axles and small tires.

I think the 727 is a pig of a tranny compared to others. Phoebe is running a TH400/QT right? TH400 is a whole other animal and transfers power more efficiently than a 727.

I have heard both arguments RE: T400 vs. 727 for sucking power but I can tell you my 401 in the GW has never got better than 12.8 and that was the last tank before the axle broke with 35s on 3.73 gears.

well I can't speak for a TH400. but so far I'm really liking the 700R4. It has a lower first gear than a 727, giving it pretty good oomph off the line. I'm also liking the 4th gear and the TCC. I've got it wired on a switch so I can turn the lockup on/off.

Unfortunately, the 700R4 has something loose in there that is rattling around pretty bad. I'm gonna have to drop the pan to investigate....

Blake wrote:I'm gonna hook it up to the water pump then...

Newer GM trucks are that way, after about mid 90's I think.

Well I connected the heater hose to the water pump and capped off the radiator. Took it for a test drive about half a mile down the street, filled up with gas (while idling) then drove it home. Temp gauges just barley moved and the heater blew cold air. Heater hoses were only luke warm.

Pic of the engine bay. Electric fan works on a switch and I've been leaving it off.

Grabbed an auto dimming rear view mirror with compass and temp gauge from the junkyard. I think it was from an 03 suburban. The temp gauge isn't working correctly.



Pic of the interior. Some of you with a keen eye may notice some irregularities here. There's a late model GW tilt steering column and driver side door panel (passenger side is stock for the J20). I'm also running the engine/dash wiring harness from an '89 GW. Behind the stock '74 cluster is a quick connect harness that I made. Allows me to remove the instrument cluster in less than 1 minute.

Did you get the temp sensor itself from up by the bumper?


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Yeah, I have a couple of temp sensors and they both say the same thing. I think I actually ended up with the wrong temp sensors and need to get one of the later ones.

Ok, I know you said it is a new thermostat, but all your symptoms point to a thermostat. I would pull it a check it, maybe a little piece of gunk got stuck in it and is keeping it open a little or something, or maybe it is just defective, quality control aint all it used to be.

Update!

Replaced the thermostat and heater core. Heater works great now! I think the thermostat was the culprit.

We picked up a load of firewood and then took it for an 70 mile trip. Ended up getting 16.2 mpg (but this was mountain roads and loaded with firewood). Unloaded the wood and then took it on a 95 mile trip. Mostly highway. I need to fill up the tank and check the numbers, but I think the little V6 can get 18mpg on the hwy.

Here is the bad.

The 4.3l V6 is leaking oil (bad) out the driver side head. No oil in water or water in oil. Leaking HG? Starts and runs like a top. No smoke, no knocking, etc.
The 700R4 has an issue where the 4th gear just stops working and then the whole tranny doesn't shift right. I think the 3/4 clutch packs are fried which is common for these trannies.

So its actually leaking out the head gasket area, not the valve cover area? While that is possible, its exceedingly rare as there is typically not enough oil pressure to blow the gasket. In a water/oil mix situation its the water that blows into the oil side.

Fuel economy sounds like it is inline with 258 equipped FSJ's. My J-10 would regularly get 17mpg on the HWY back when it was stock.

Yeah, it's leaking out the head (not the valve covers). I can clearly see a line of oil that starts at the head gasket and goes down.

UH-huh. From the same guy that said the thermostat was OK.


(sorry Blake, could not even help myself on that)