Coolant hose routing question

[68isgreat]

Hi guys, I have a 68 shorty stepside I've done a frame off on, and I'm installing a 1990 350 tbi motor in it with about 90k miles supposedly, and a newly rebuilt (supposedly) 700r4 with less than 1k miles on it. This was a farm truck with a six banger, so I'm starting from scratch. I just got a new painless harness and will be installing a rear efi tank soon. Right now, I have the coolant hose outlet at the rear of the intake manifold capped off, as well as the one from the top of my radiator, which is from a square body, so it has the two upper inlet hoses. Before I hook the hoses up to the heater core (the cab is still off the frame), I just want to see if it runs ok. Can I hook up the rear manifold outlet hose to the upper right outlet hose on the radiator temporarily just to see how it runs? I don't want it to overheat. Just want to make sure that's the correct coolant flow, from the rear outlet (which would normally go to the heater core inlet) and back to the radiator, which would flow down to the lower radiator hose and up to the water pump. I can post a pic if necessary.

Thanks!

[MikeB]

Not sure what you mean about a coolant hose outlet at the rear of the intake manifold. How about some photos?

[54blackhornet]

Most of the older engines had the outlet on the front passenger side of the intake. I have mine looped because the heater core has a leak. Intake to water pump, works fine.

[weq92f]

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You should be able to run it for a short time with no coolant without causing any damage. If you just wanna make sure it'll start and run, go for it...don't mess with the cooling system at all.

Just remove the belt(s) and fire it up.

-klb

[chewychevy67]

On tbi 90's engines there is a coolant line from the rear of the intake by the dizzy hole. I think this is what the op is referring to.

[68isgreat]

Originally Posted by weq92f

.

You should be able to run it for a short time with no coolant without causing any damage. If you just wanna make sure it'll start and run, go for it...don't mess with the cooling system at all.

Just remove the belt(s) and fire it up.

-klb

Thanks! I might do this.

[68isgreat]

Originally Posted by chewychevy67

On tbi 90's engines there is a coolant line from the rear of the intake by the dizzy hole. I think this is what the op is referring to.

Yes that is correct. I have that outlet capped and was just wondering if I should loop it back to the top passenger side hose on the radiator, which is the same size hose. Not sure if the water needs to flow in a loop like that, or if it can remain capped until I get the heater hooked up?

Also, my tbi doesn't have the vacuum tube coming out the drivers side front that loops back towards the firewall as shown in the pic above. Do I need to have that hooked up, or can I just cap it off? Someone removed the EGR system and capped it off on the manifold. I'm not even sure what that tube is supposed to hook up to? I'll try to post some pics soon. I just ordered a bed mount efi gas tank, so I'll be firing it up here in the next few weeks.