tbi to l31 vortec swap. have questions about timing cover and coolant bypass????

[fish4hc]

factory TBI runs the 3/4" heater hose to the intake. plug the one in the pump, and hook it to the intake.







My truck has the heater hose going from the water pump to the heater core and the heater core to the intake. Should it be different. This is how it appears to be stock?

[GreaseDog]

My truck has the heater hose going from the water pump to the heater core and the heater core to the intake. Should it be different. This is how it appears to be stock?

do you not have a heater hose that connects to the passenger side tank on the radiator? or a plugged "nipple" where one would go?

[fish4hc]

I have the upper and lower radiator hoses obviously, and the heater core hoses in which one goes through the intake.


I guess im just going to plug the hole in the new intake for the bypass and drill some holes in the t stat. How many holes should I drill and what diameter?

Otherwise, looks like everything is on track. I got a egr hose from the junk yard but its to short to run from the front of the intake to the bung hole on my headers on the collector so I extended the line with a fitting and some metal flex line.

[woody80z28]

I would like some clarification on the heater bypass if possible.

I just swapped Vortecs on my truck with a carb intake. The stock TBI had a heater hose from the rear of the intake to the core and then from the core to the radiator. I moved my heater feed hose to the front of the intake next to the tstat. Recently I noticed the coolant bubbles, and it foamed out the rad filler when I gave it a quick rev with the cap off. Could this be due to my heater line setup? I'm using the stock TBI pump and engine block and no holes in the tstat.

I know bubbles in the rad are generally caused by a bad head or head gasket, but both are brand new in my case and there is no coolant/oil contamination and it runs great.

[woody80z28]

Bump. I tried a chemical test on the coolant and it tested ok - no hydrocarbons. So it must be something with the coolant hose routing.

[darksurfer11]

do you not have a heater hose that connects to the passenger side tank on the radiator? or a plugged "nipple" where one would go?

Hey, I am running into this right now, I have the GMPP tbi to vortec intake. The rear coolant line goes to the heater core and the one nipple on the TBI water pump also goes to the core. Could I run the front coolant port on the intake to the nipple on the passenger side of the radiator that is currently plugged?

[GreaseDog]

I would like some clarification on the heater bypass if possible.

I just swapped Vortecs on my truck with a carb intake. The stock TBI had a heater hose from the rear of the intake to the core and then from the core to the radiator. I moved my heater feed hose to the front of the intake next to the tstat. Recently I noticed the coolant bubbles, and it foamed out the rad filler when I gave it a quick rev with the cap off. Could this be due to my heater line setup? I'm using the stock TBI pump and engine block and no holes in the tstat.

I know bubbles in the rad are generally caused by a bad head or head gasket, but both are brand new in my case and there is no coolant/oil contamination and it runs great.

hmmm, I have had issues with coolant bubbles all along... Do you notice a gurgling sound from the heater box from time to time as well?

[GreaseDog]

Anybody else ever notice the gurgling sounds?

[woody80z28]

Anybody else ever notice the gurgling sounds?

Yes, I had noticed it. I ran a hose from the w/p to the intake and it has been good.