Need suggestions as to what the issue might be. LS swapped 1950 Chevy. Sorry about the huge long thread but I'm a noob, I searched a few keywords before making this.

Swapped 5.3 with all LS1 accessories swapped onto the motor, including new waterpump with all gaskets and such, Speedway Motors aluminum radiator modified slightly modified for use in the car. The thermostat housing was re-clocked but the main body of the housing was not touched. I removed the factory thermostat from the housing because I knew it would be getting welded on and figured the rubber seal in the thermostat would get destroyed from the welding temps anyways.

Once the thermostat housing and radiator were done and I could not get that factory thermostat back into the housing the spring tension was far too great so I went and bought a stock thermostat and housing since thats how they sell them. I removed the thermostat from that housing and it went into my modified one with very little issue (was tough but nowhere near as bad as the original)

I ran the motor for about 10 minutes and the i kept an eye on everything, no gauges installed yet since I'm not fully done with it all yet. But I felt the hoses, felt the radiator tanks and all that. The electric fan kicked on which I believe the computer was set to kick on at 180 and to 160 right now.

I ran the steam tube to the radiator overflow fitting on the filler neck just so it had somewhere to go at the moment but noticed that the thermostat housing was hot but the hose and pipe on the lower radiator were not hot at all, the radiator tank on the drivers side was cool to the touch also (both inlet/out are on the passengers side tank though)

I removed the radiator cap (some random unknown cap I had laying around since they dont supply them with the aftermarkets it seems) and it didnt seem that the coolant was circulating, i squeezed the upper hose and the coolant came up to edge about to flow out the filler but I quit and it didnt seem to go back down either...very little if anything.

Did the thermostat not open? Did the steam tube being ran to the overflow mess something up? I also tried blocking off the steam tube for a few minutes and did nothing. Now I'm having issues keeping it to run after that issue...sometimes fires up but sputtering and struggling to run and dying and it seems I lost my throttle from the FBW to the T.B. and such...doesnt seems to wanna stay running, throwing a few codes like: PCM to TAC module but it was working great prior to the radiator install & generator F & L-terminal.

Have a member on here coming to take a look tomorrow to see what the deal is but looking for additional insight/thoughts?

 

Pics of setup:

I think I'm going to have a bung/fitting for the steam tube welded into the radiator tank, should I have it done on a specific tank side?

 

if the guy didn't disconnect all the grounds before welding on the car, that could have fried some things

 

Welding the radiator & termostat were done in the car but he disconnected the computer and there was no power ran to the battery. Like I said, I ran the car afterwards and it was running excellent for about 10 minutes but seemed like it was loosing power or something as it started to idle lower and lower until it was struggling to run and just died, then wouldn't start again after many tries and when it did was only for seconds.

I did blow a fuse that was wired in line for the relays when the fan kicked on but the funny part is that the fan relay fuse isnt the one that was blowing when it tried to kick on, it was for the computer I believe. It was only a 15a fuse.. I upped it to a 25a to see what happened and it seems work fine as I was kicking it on and off using the scanner but still wont run. When it does start its barely running and I have no throttle all of the sudden, quickly feathering the pedal barely gets any response out of the T.B. and will eventually die. I gave up at that point.

 

how's the fuel pressure looking joe?

 

That I am not sure of either at the moment, no gauge to check it. It's a brand new Walbro 255 inline pump & corvette regulator/filter and the pump is running strong when you turn the ignition over it primes and can be heard running...I assume I will have to check it. Is there a tester gauge I can pick up to get an idea from the pressure valve on the rail?

 

screw a fitting into one of the -6 lines would be a choice, otherwise start it and spray some starting fluid down the throttle bores, if it runs a ton better, you know something is up. What kind of codes are you showing? I bet they will help you out a ton.

 

My thoughts on the cooling issues are this:

Thefan is tuned to kick on at 180 and now I'm reading that most thermostats are set to open at 190 on the ls motors? If this is true the thermostat would have never gotten a chace to open if the fan was working like it should. Anyone agree that is a veru high possibility?

 

Here are the codes I got after all this b.s. started when the engine died the first time:

engine speed output problem, mil control circuit problem, engine oil pressure sensor circuit low, fuel level sensor circuit signal high/open, evap pressure sensor signal low, evap system vent control circuit low, evap purge control circuit fault, trans range sensor circuit out of range, pcm to tac module serial data, and generator L & F-terminal

 

I have 2 possible diagnosis of your engine after reading your posts, to me it sounds like your engine is starting to seize up either due to lack of lubrication or lack of cooling. When you did this swap did you change the oil pan or the oil pump pick up tube o-ring it is common to pinch the o-ring and thus causing a lack of oil pressure or no oil pressure causing the engine to seize, and it will start to act like your description after running for 5-10 minutes, it can run for up to 10 minutes on very low oil pressure due to a slightly pinched o-ring, and then it will seize up. Or possibly you ran it for too long without properly purging the cooling system of air causing a hot air pocket and no coolant circulation and this could also cause the engine to seize up as well. I'm leaning more toward the first diagnosis, what do you think?

 

I did swap the oil pan, pickup, windage tray, dipstick and tube. I did not damage the o-ring on the pickup tube. it went up straight and I felt around the flange to make sure it bolted up evenly and tight. It still turned over just fine but just wont fire up and when it does its only for a 15 or so seconds. Starving for fuel or air or maybe the T.B. took a ****?

The motor only ran for about 10 minutes, just long enough for the fan to kick on but I think there was a heavy draw causing the computer fuse to blow which was made into the newly wired harness for the relay. I figured computer because ignition on was just cranking and cranking without hearing the pump and the fan didnt kick on nor did I hear the relays clicking. Nowhere near hot or even overheating though.

 

Hopefully everything turns out ok for you, just one suggestion for you before you fire the engine again I would definitely hook up a set of quality gauges to verify your oil pressure and water temperature are within the proper operating range. I have seen the pickups that visually look fine when they are tightened down only to find the o-ring pinched so bad a chunk was cut out of it, with your gauges you can sleep better knowing you have the proper oil pressure. Good Luck

 

The Diagnosis ...
20 PSI Fuel pressure , Motor idling at 300 RPM.

One new fuel pump later pour in 6 gallons of gas , and runs great...

Still has a Bum o2 tho. Bank 1 Sensor 2