lt1 radiator problem

[Oldskool153]

ok so i have prolly one of the cleanest all orignal (minus the c5 wheels and exhaust) 94z28. My radiator leaks when i shut the car off, at first it was a minor drip, then it would leave a puddle once every 3 or 4 times I would take it out, now 2 months later its a puddle almost everytime I take it out, i can have my mechanic change it for $300 (total parts and labor) but due to the fact that im currently turning an old gmc truck into a streetrod I dont really wanna spend the $300. Im thinking of changing it myself or depending on how bad the crack is jb welding it for now. Has anyone done a radiator on an lt1? im used to working on my own stuff but most of it has been 1970 or older so i usually send the lt1 to the mechanic, so how hard is this gonna be and how long can i expect the swap to take?

[S.J.SLEEPER]

lt1 rad not hard to do at all. bout 2 hours,
drain rad
disconnect hosed
diconnect 2 plugs for fans
pull upper rad shroud off
slide fan assy up & out
disconect cooler lines
slide rad out
repeat process back in

good idea to install new thermostat & drill a 5/32 or 1/8 hole in thermostat so that when you fill back up with coolant it doesn't get airbound

fill rad, squeeze hoses a bunch of times to see air pockets buble out. cap t 1 click, run at idle for bout 30-40min with heat on full blast, make sure you see the fans turn on & off twice so you know thermostat is opening and cycling the water through.

good luck, if anywhere in the nearby jersey shore area i could give you hand and also lend you a coolant overflow funnel (helps bleed system out of air)

[Oldskool153]

thanks im about 2 hours from the jersey shore lol, but im also concerned with my coolant level sensor, now even when i fill my radiator up to the proper level the low coolant light is on, is that do to air in the system?

[S.J.SLEEPER]

thanks im about 2 hours from the jersey shore lol, but im also concerned with my coolant level sensor, now even when i fill my radiator up to the proper level the low coolant light is on, is that do to air in the system?

check to see if plug is seated into sensor, if so then unplug sensor(i believe passanger side 3/4 way up tank)
see if light is off or on, then take a paper clip and jump terminals on plug, light should go off or on. if it changes then that means the sensor itself is bad. if no change light on or off then you have a wiring issue (plug grounding out in harness somwhere) but i doubt that will be the case.

hope i was of some help.

[Oldskool153]

yea thanks, im gonna go start tearing it apart today, ill post any results

[sweetbmxrider]

usually the sensors get gummed up. might be able to clean it when you swap radiators and see if that helps. hardest part of swapping an lt1 radiator would be bleeding the air properly.

[LTb1ow]

Bleeding it is not bad.

Do you know where it is leaking? The ends are replaceable, that may be cheaper than getting a new radiator. The low coolant sensor likes to play games, if you know you have coolant, leave it be for a few heat cycles. Do not go drilling holes in the thermo, and it is also a good idea to get a new 160 or 180 thermo, remember to get a LT1 specific one. It is NOT a SBC thermo.

As for the bleeding... fill the system with the bleeders open, when they begin to drip coolant, shut em, put on rad cap and start car. Let it heat up and then crack the bleeders with a rag under them. Basically it, do that a few times and you will be set.

Best site for good info.
http://shbox.com/1/4th_gen_tech2.html#cooling

[vipergtx500]

the low coolant sensors have failed on each lt1 car i've owned, i just got fed up with my current one and unplugged it, just gotta check the level often enough to be safe. With the thermostat make sure to go the lt1 specific one like mentioned above, our cooling system uses reverse cooling. Be patient with the bleeding too, the coolant will eventually come out it might take a few minutes

[Oldskool153]

hey guys, got the rad out and found a small crack on one of the seams on the passenger side plastic endcap, i sanded it, and filled it with jbweld, let it dry overnight and put it back in the car (whole job as well as bleeding was very simple to my suprise) it stopped the leaking for afew hours but i can still see a very tiny drip comming from the jbweld which tells me its only a temporary job, I called the Chevy dealer and i can buy just the plastic end for 60bucks, but they cant tell me how it fits on? do i need to get it pressed or does it snap in?

[BonzoHansen]

JB Weld will not work! If nothing else vibration would kill in ASAP. New rad is ~$120 from rock auto. I think they sell tanks too. But I'd not even bother.

[LTb1ow]

yea but he does not need the full radiator. Only the end piece, why spend the extra money?

[BonzoHansen]

My theory is if one tank cracked, the other is one the way. Then you still have a 15 year old core and no warranty. Seems pennywise & pound foolish to replace one tank. Hell, the coolant cost of doing it twice wipes out a chunk of the savings. If i were sellgin the car tomorrow, maybe. Otherwise a new rad 125 seems the ticket to me.

[LTb1ow]

Wisdom comes with age I guess.

Probably would be easier to replace a whole radiator too.

[Oldskool153]

yea im just gonna order a new one, theres a few new ones on craigslist for like $75 that differant ppl bought and didnt need. will any lt1 fbody radiator work as long as it cam from an auto?

[LTb1ow]

Yea. Should be fine. You cannot get an LS1 one though.

[Oldskool153]

btw i should do this asap, cuz as of right now im running straight water and stopleak, which prolly isnt good, but im not gonna keep wasting coolant and have it all leak out. atleast its summer ha

[LTb1ow]

Just get distilled water. Its fine to run straight water if the temp does not go below freezing. We used to get florida boats that ran straight water all the time.

[BonzoHansen]

Stop leak has it's own issues too. I'd flush that system out. Then coolant & distilled water.

Wisdom comes with age I guess.

Probably would be easier to replace a whole radiator too.

Yeah, redo enough jobs and you learn.

[Oldskool153]

Yea i wanna get a new radiator, if u open my cap the water is now a brown mixture from the stopleak it looks bad im sure it cant be good for my motor.(although its not running hot) So i found a guy that has a "$500 aluminum race radiator" atleast thats what he says he paid for it, he said that its almost brandnew and that i can use it with my stock motor, he said at this point he would take $50.. something fishy?? also once i put the new radiator in how do i flush the water/stopleak out of my block??

[sweetbmxrider]

just get a stock replacement. not only will it help keep your all-originalness going on, it will fit and work correctly.

[vipergtx500]

on my old 95 formula a hole formed in the plastic and i used quiksteel, you can find it at pepboys, it worked, sealed dried and never leaked again, but i could of just been lucky, if that happened now a days i would just get a new radiator to play it safe. just go with the stock replacement, $50 for a $500 radiator sounds odd, if its took good to be true it usually is.

[LTb1ow]

As to flush the system, get it all together, and then only use water, keep dumping it, and refilling with clean water.

[Oldskool153]

thanks guys...any of you going to the Camaro show in vineland Sept 13?? It was in cruzin news mag, all gens welcome should be decent size..

[BonzoHansen]

It's on my calendar. Check the other events forum.

/hijack

[V]

any lt1 rad will work, auto or M6. The manual ones just have the holes for the trans cooler plugged usually.

[JerzLT1]

check to make sure its not your water pump...

edit: also please do not drill a hole in your thermostat, Bleed it the way Showsomepromise said and youll be fine. as for the coolant lvl sensor, its 15 bucks just replace it

[Oldskool153]

i changed the radiator so far so good, my friends buddy was strippen his 94z so i gave him $50 for his radiator, and I just put a performance transcooler on her today too

[LTb1ow]

Nice, good job.

[sab123]

When I got my car, the radiator was leaking from under the plug where the automatic trans cooler would connect. It would leak only at high RPM and temperature, when there is more pressure in the system. Fixed by changing the radiator :-)

[Oldskool153]

yea my old radiator wasnt leaking from the transline but the one i put in was, running the translines threw a seperate trans cooler seems to have solved the prob, plus my motor runs cooler now cus the radiator only has to cool my coolant