chevy 350 overheat! simple help! TPI guys!

customjeepyj

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Feb 12, 2011
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I have a 95 yj with chevy 350. Had a carb on it and it ran fine and cool, had throttle body injection on it and it ran fine and cool, put turned port on it and now it runs hot. It will start fine run fine and the temp will slowly climb untill it boils. year old water pump brand new thermostat same all aluminum summit radiator, same electric fan by the way is feeling a little weeker. never overheated with any other setup untill I put tpi on it. The only thing that is different is the top radiator hose is a little longer and goes above the block and radiator, but with the cap off and the motor running you can see water flow. Is there something I am missing on the tpi? please help
 
did you add a crosover tube?
 
I think the TPI was a reverse cooled engine. The water pump turns backwards from an old school standard 350. I wonder if that is the issue. Google and call Arizona Speed and Marine. They are the tpi swap masters. I used thier stuff back in the day and they are very sharp on TPI engines.
 
Thanks sounds great!! Already thought bout that and talked to a guy larrys electric, he said should be fine but something is up! That's for sure I'll call thanks again.
 
Just a few random thoughts... They may all be :poop: but I thought I would throw them on here for ya'.

I remember my LT1 with reverse cooling having a bleeder screw that let the trapped air out of the cooling system. But, I dont think that comes into play with your tpi. As long as the radiator is higher than the intake, it should bleed itself.


If the water is flowing good it shouldnt be a stuck Thermostat.
have you watched the gauge to see the stat popping open?


Did you check that the intake gaskets matched up properly to the water ports in the head and intake? I dont remember TPI's well enough any more. Do they match the standard 1403 felpro intake gasket?

Timing or a lean fuel mixture can get one hot too. You have messed with both lately.

As I remember, you had 305's in Camaros and 350's in Vettes.
If you have the 19lbhr injectors from a 305 it may be leaning you out and making it hot. For a stock to mildly healthy 350 you will need the 22lbhr Vette units or bigger and the adjustable fuel pressure regulator and gauge to keep it in the upper 40's on fuel psi at the manifold.

An in-tank fuel pump works way better than a frame mounted pump. The frame mounted pumps can/will starve the engine if it isnt mounted below and close to the tank. They dont suction fuel uphill very well and they get hot trying.

Cant remember if you have to unhook a wire from the distributor when you set your timming. (On a TBI its a brown wire).
Good luck.
 
Yea you have to unhook the wire and I have a walbro 60 psi pump and 22 lb injectors I'll have to pull plugs again see if it is running lean thanks y'all hopefully figure it out driving me crazy
 
ok found out its not reverse flow and its not running lean. gonna check for codes next. spark plugs looked normal. Any other suggestions? i think my fan lost its balls and I have a crazy long tall hose on the upper side or the radaitor and intake. but people run radiators to the bed of there buggys so i ruled that out but maybe i need to take another look,
 
Put a big shop fan in front of the grill and see if the temp stays down. That "should" eliminate the pump and make the fan the culprit. If that upper hose is routed up high above the raditor and intake it could be holding air. The last time it ran with the previous set up all was good, right?
It's about gotta' be something you have changed from the last set up. :popcorn:
 
The reason the the crossover tube question, there is a head difference in certain years where if you swap the top end you will starve half your engine from jacket water flow. Usually when converting To TPI you need the crossover.

If you have acces to atemp gun it would be interesting to see the temp differential after it warms but before it runs hot.
 
got a temp gun today from a friend! where and how do you make the crossover? at the back of the heads somewhere? Thanks!! Be great to go wheeling without overheating. havent even got the motor broke in yet!
 
overheating

i have a early 90,s 350 block with vortec heads and carburated intake. i had to make a bypass with my heater hose. in the summer when i cut my heater off mine would run hot.i had to make a bypass between the inlet and outlet so water would continue to circulate. evidently there is no bypass in the heads or block. this works for me if you have any questions call me 864-812-7051 this drove me crazy for almost a year.
 
bypass

i have a early 90,s 350 block with vortec heads and carburated intake. i had to make a bypass with my heater hose. in the summer when i cut my heater off mine would run hot.i had to make a bypass between the inlet and outlet so water would continue to circulate. evidently there is no bypass in the heads or block. this works for me if you have any questions call me 864-812-7051 this drove me crazy for almost a year.

Thanks! You are just talking about a tee between the heater box inlet and outlet right? Just for the coolant to keep circulating. That makes since I just never thought of it because it never overheated before untill the tuned port intake. One more thing, does your heat still work good in the winter with the bypass?
 
i have a early 90,s 350 block with vortec heads and carburated intake. i had to make a bypass with my heater hose. in the summer when i cut my heater off mine would run hot.i had to make a bypass between the inlet and outlet so water would continue to circulate. evidently there is no bypass in the heads or block. this works for me if you have any questions call me 864-812-7051 this drove me crazy for almost a year.

Just curious... Are you running a reverse rotation water pump or standard direction? I am wondering if that plays a large part in it. Vortecs with serpentine belts were reverse rotation. If you are turning that pump the wrong direction you are not moving much water pressure.
 
well drilled couple holes in the t-stat and adjusted timing again and fixed leaky intake gasket. Going to callalantee this weekend so we will see lol
 
does it have the hose from the water pump to the intake in place i think it's a 5/8-3/4 dia ??.

No hose to the intake. This weekend of course overheated, water pump stated leaking out the little weep hole so I replaced it then went wheelin again and it go up to 215 so I came back to camp. I didn't let it get any hotter it jst keeps climbing slowy until it overheats. I just gonna throw a old clutch fan on it see if that helps. Just out of ideas. Thanks.
 
Fixed! Good ol Ford Taurus fan fixed her up. Alot more air flow. Now for a new alternator just to run that thing! Just don't understand why all of the sudden that fan is not enough. Been good enough on tbi and carb.
 
Fixed! Good ol Ford Taurus fan fixed her up. Alot more air flow. Now for a new alternator just to run that thing! Just don't understand why all of the sudden that fan is not enough. Been good enough on tbi and carb.
It has'nt fixed it, it is overcompensating. No good reason for the TPI intake to make it run hotter than the others. What happened with that cross over hose the other guy was telling you about? Just curious incase I run into the same issue one day.
 
No crossover that I seen or know how to fab up besides removing the heads and drill and tap like a lt1. The intake runs the same as others from what I can tell. Talked to larry's electric (tpi guy who sales harness and other things) and says everything is the same as the other intakes the way the coolant runs. I know it doesn't run in reverse like lt1. I guess my electric fan was slowy biting the dust because I didn't have a thermal controller or anything just ran it all the time.
 
I had the same problem on my 90YJ with a 91 vette L98 TPI vette motor. no crossover tubes.

no fan would cool it except a taurus fan, tried every one on the market including a fancy shiny new aluminum radiator.

the TPI motors like to run around 210 anyway, IIRC they have a 195 t-stat so once it gets over that its hard to bring back with a convential low flow fan.
 
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