Blowby advice

[Ωhm]

Check you sender (back of block). Disconnect wire. Connect DVOM (top of sender to battery ground). Look for resistance (Ω's) values as follows. Compare reading to IC gauge.

 

[llhat]

5 hours ago, Eagle_SX4 said:

Have you checked the temperature of your heater core hoses and upper radiator hose by touching them? They should feel about the same temp. If not it could be the heater control valve which shuts off the flow of coolant into the heater core when it's not being used.

 

 

3 hours ago, GonzoTheGreat said:

because that is the vacuum line that operates the heater valve. That is what allows the flow of coolant to the heater core. You need that. 
 

I don’t remember off-hand if the valve is closed WITH or WITHOUT vacuum. I’m away from my trucks at the moment. Maybe someone else can jump in with that info. 

 

can anyone confirm IF this valve is Normally open (allowing coolant flow all the time) or Normally Closed, allowing coolant flow only with vacuum on the line?

 

i've seen descriptions of 'both ways' but no confirmation...   

 

one post indicated this valve had vacuum applied when in A/C mode to cut off coolant flow to the heater core...

 

what is truth?

[Ωhm]

[llhat]

Really thank you for that table!    It is of assistance,  but I am a bit dense....   and my confidence has waned in the past couple years.... 

 

appears there's two lever positions where the water valve is closed,  does this mean vacuum is absent at the pink line connecting it or there's vacuum applied?

 

Logic sort of indicated the valve allows flow in a normal state, and closes when either in OFF or Vent,  ? by application of vacuum.....

Next time i am messing around will investigate with a vacuum gage ...........

[Ωhm]

53 minutes ago, llhat said:

Logic sort of indicated the valve allows flow in a normal state, and closes when either in OFF or Vent,  ? by application of vacuum.....

 

For "Max A/C or Norm A/C" use note number (5).

 

53 minutes ago, llhat said:

It is of assistance,  but I am a bit dense....   and my confidence has waned in the past couple years.... 

 

I'll join you here, truth table is difficult to read, let alone understand. My gut tells me, default (no vacuum) is water will flow through the valve for no other reason than safety concerns (defrost mode).

[llhat]

thank you again ...

[Whitaker717]

I hit my thermostat today so I may try to replace it while it’s nice. Anyone have step by step instructions for this closed system? 

[Pete M]

11 hours ago, Whitaker717 said:

I hit my thermostat today so I may try to replace it while it’s nice. Anyone have step by step instructions for this closed system? 

 

are you wanting to do other things too? (such as a flush/fill or replace the water pump)  or just replace the t-stat? 

[Whitaker717]

2 hours ago, Pete M said:

 

are you wanting to do other things too? (such as a flush/fill or replace the water pump)  or just replace the t-stat? 

Just the tstat. Water pump is only 2 years old. Just looking to replace the thermostat and refill my coolant with no air. Not sure how much to get though or really even do it. I’m going to give her the ole college try though. Lol

[Pete M]

not much coolant will come out if you're just doing the t-stat.  grab a jug of 50/50

 

youtube should have a bunch of videos on it.  

[Whitaker717]

4 hours ago, Pete M said:

not much coolant will come out if you're just doing the t-stat.  grab a jug of 50/50

 

youtube should have a bunch of videos on it.  

Shockingly Pete I couldn’t find any for a closed system. 

[75sv1]

Also, if you park on an incline, nose up, there is less coolant that comes out.

[Whitaker717]

1 hour ago, 75sv1 said:

Also, if you park on an incline, nose up, there is less coolant that comes out.

I have never done it, so it should be interesting. I have yet to find any videos on it so I will try my best

 

[Pete M]

you're right, I couldn't find a video that covered the whole thing. 

 

 

lemme see if I can remember all the steps.

 

-start nose up and remove all the things in your way

-loosen temp sensor so you know it's not stuck

-remove t-stat housing and catch fluid

-clean mating surfaces

-drill little hole in t-stat if it doesn't already have one

-install t-stat using a tiny drop of gasket maker at 12oclock to hold it in place

-install housing using gasket (I prefer using a gasket with no sealant because a dry gasket doesn't care about a coolant dribble and it makes the job easier next year after the t-stat fails, lol)

-remove temp sensor

-pull rad hose and fill until fluid comes out temp sensor hole

-put everything back together

-fire up engine and check for leaks

-loosen temp sensor to remove any bubbles

-tighten back up and let truck warm up

-check for leaks and overheating

-keep an eye on the overflow bottle level and add as necessary

 

 

 

 

[GonzoTheGreat]

Also, pro tip, let the engine cool before you open anything. 

[Pete M]

yup.  especially don't bleed from the sensor with a hot engine. 

[Whitaker717]

On 2/25/2025 at 3:22 PM, Pete M said:

you're right, I couldn't find a video that covered the whole thing. 

 

 

lemme see if I can remember all the steps.

 

-start nose up and remove all the things in your way

-loosen temp sensor so you know it's not stuck

-remove t-stat housing and catch fluid

-clean mating surfaces

-drill little hole in t-stat if it doesn't already have one

-install t-stat using a tiny drop of gasket maker at 12oclock to hold it in place

-install housing using gasket (I prefer using a gasket with no sealant because a dry gasket doesn't care about a coolant dribble and it makes the job easier next year after the t-stat fails, lol)

-remove temp sensor

-pull rad hose and fill until fluid comes out temp sensor hole

-put everything back together

-fire up engine and check for leaks

-loosen temp sensor to remove any bubbles

-tighten back up and let truck warm up

-check for leaks and overheating

-keep an eye on the overflow bottle level and add as necessary

 

 

 

 

Hey Pete, today is the day I try the thermostat. Couple quick questions and I think I am ready. So you totally remove the temperature sensor before-filling? And do you fill the new coolant through the radiator hose as well instead of the bottle? Thanks

[Pete M]

I would remove the sensor during filing so that air (and eventually some fluid) can easily escape.  later on it'll be pressurized by the running engine and so you only need a small hole for any trapped air to escape.  I always fill through one of the hoses.  the pressure bottle just needs to be kept at the proper level. 

[Whitaker717]

1 hour ago, Pete M said:

I would remove the sensor during filing so that air (and eventually some fluid) can easily escape.  later on it'll be pressurized by the running engine and so you only need a small hole for any trapped air to escape.  I always fill through one of the hoses.  the pressure bottle just needs to be kept at the proper level. 

Awesome. Thanks Pete. I’m going to give her the ole college try

[Pete M]

just don't bleed it when the engine is hot.

[Whitaker717]

1 minute ago, Pete M said:

just don't bleed it when the engine is hot.

I got it all done. I started it and unscrewed the sensor and it started coming out. I quickly screwed it back in. Lol. Hopefully I did it right. Seems to be ok so far. Now I just can’t get my vents to work properly. 🤦🏻‍♂️