Fast355

iTrader: (2)

I think it will run alot cooler. Those 5/8" heater hoses flow like garden hoses even at idle.

RS-Chevy-SS

Yeah I've noticed that when filling the radiator. Think ill have to drain the coolant to plug the ports on the intake and WP?

Have you actually gone through this already?

Spaceboy1980

iTrader: (6)

I may be wrong on this but I believe the heater lines will only flow when the heat is turned on. There is a vacuum line running from the selector to the valve for the heater lines. When the heater is off the flow is cut off.

Now what does this mean when you do not run a bypass? Well now your water flow is dead heading at the thermostat when closed. An external bypass is nothing new, Oldsmobile had been doing it with all of there later model V8s (look a the waterneck for a 260-455).

If you are having cooling issues it can't hurt to try blocking it. Keep in mind I am running more HP, a previously sludged up radiator and my original TBI fan and having absolutely no cooling issues. The hose for the bypass is tiny and besides it is pushing no water past the thermostat, it can only return via the waterneck. Once the thermostat opens the water is going to flow to the point of least resistance and pressure. The water is being pressurized inside the block, why would it go that way instead of the lower pressure upper hose?

RS-Chevy-SS

I think mine and your bypass are routed differently. Mine is bypassing just before the water neck and dumping it back into the WP inlet. Just pulling hot water and dumping it back in without cooling. What is your average ambient temp? And do you run ac? I can run cold all day, without AC.

Reference the heater hose. When routed as factory, with heat off, the valve bypasses the core and sends coolant from the intake manifold directly to the radiator. When heat is activated the valve sends coolant to the core, then to the radiator. Regardless of heat selection, it is always flowing. You can see this by popping the rad cap on a cold motor running.

Spaceboy1980

iTrader: (6)

Is there three lines coming from the valve, I cannot remember and am out of town away from my car right now?

Mine cools fine with the AC on. My bypass comes from my water pump to just below the waterneck. It will only bypass when the thermostat is closed, if the water gets hotter than the thermostat then it will open allowing the water to flow to the lower pressure area beyond it.

RS-Chevy-SS

Theres 4 lines. One from the intake, one to the core, one from the core, and one to the radiator.

Fast355

iTrader: (2)

Which is flawed thinking. Water will take the path of least resistance which happens to be the suction side of the water pump not the radiator core.

Fast355

iTrader: (2)

I eliminated the bypass on my Vortec 5.7 Express when I put the marine intake on it and it stays cooler than ever.

Spaceboy1980

iTrader: (6)

It can only run cooler if you are having cooling problems to begin with. If the heater valve always flows and doesn't dead head then it is very possible for it to function as a bypass, I would have to examine the system on my car before I could say for sure.

You are right, the water that the hose can support would be pulled into the suction side of the pump. Once warmed up however you cannot go below your thermostat temp unless you have a failing thermostat that is sticking open thus you cannot run cooler. My luck is that they always fail in the closed position, lol.

They system is pretty aweful though. Giving it some actual thought, some holes drilled into the rim of the thermostat would make for a better system. It would eliminate any dead heading, that is if it is even necessary. The case against it is compelling.

RS-Chevy-SS

Well I am having cooling issues, but not to the point of overheating. Just running to close to 215 for my comfort. Only with ac on.

Im not gettin what you mean about going lower than TStat temp. My TStat is a 180. If I run 180 at all times ill be happy. The problem with the bypass isn't trying to lower temp below TStat, but the fact that is constantly pulls and dumps hot water back into the WP inlet. Verified heater core bypass is flowing. If you have a thirdgen spaceboy, yours should be the same if routed correctly.

Anyway, removed the bypass last night. Ran 2 1/2 black steel plugs. 1 in WP other in intake. The intake mani is seeping a little. Just enough to wet the rim of the plug. WP is fine, then again that is a suction port.

Fast, did you have any sealing issues? On my commute this morn, temp stayed at 180 with AC in ambient of 80*. Will test later in blazing heat.

Fast355

iTrader: (2)

Nope, but I use permetex thread seal on everything. Its like liquid teflon tape. Dry the fittings first with compressed air, then dab the threads and screw it on. Let it dry overnight before it touches coolant.

RS-Chevy-SS

Which one exactly did you use? I used rectorseal pipe thread sealant but only let it set for about 2.5 hours before it hit coolant.

Fast355

iTrader: (2)

This is what I use as I keep it around for sealing head bolts, intake bolts, oil pan bolts, etc. I can't stand a leaky engine or transmission.

http://www.autozone.com/autozone/acc...er=162305_0_0_

RS-Chevy-SS

Oreilly has some stuff that is by permatex, not that specific one, but says its made for oil and coolant lines. May pick that up

http://m.oreillyauto.com/mt/www.orei...0802&ppt=C2392

Fast355

iTrader: (2)

Probably the same stuff just in a different quantity. Never have had an issue with coolant or oil compatiblity with the other stuff. The head bolts are actually exposed to both.

RS-Chevy-SS

Well just got done testing this theory. I wouldn't say that the car now runs cooler. It runs about 200-210 ish right now which is about the same as before. I will say however that it appears the fan can now keep the temp relatively stable at that area, barely. Whereas before it would continue to slowly climb.

Did an idle test and it stayed at about 210ish the whole time. AC full blast. By the way Fast, I still hate that my vent temps are 60* at idle in ambient of 90*. BS.

Mind you these results are per the dash gauge. EBL commonly shows the temp about 10* cooler. It uses the sensor in the head instead of the intake mani.

Maybe I need more fan. This fan is already a beast though.

Spaceboy1980

iTrader: (6)

Something is not up to par on your cooling system. I suspect the fan myself, it is the only component that is changed aside from the motor but that cannot be scaled up. Do you have the original you can toss on there?

RS-Chevy-SS

Well you can trust me that this fan outperforms the stock single fan all day long. The fan is working as designed I think, unless the fan motor is weaker which I doubt. This fan had no problems keeping the old LO3 cool for 7 years with AC on all the way up until I did the motor swap.

The only things that haven't been changed since the swap is the radiator and the fan. I can still hear the fan and feel the fan pulling a lot of air. Maybe I just need more flow now. I am positive the stock fan can't do it though. What's the ambient temps like over there in TN? Do you run AC?

Remember my cooling problems are only with the AC on while in stop and go. On the highway it runs cool. Turn of the AC in city and it drops 20 degrees easily.

Spaceboy1980

iTrader: (6)

It gets hot here too. It has been low to mid 90s so the ac is a blowing, lol. What does your rad look like inside, is it scaley? Does the ecm agree with the gauge, it's possible for one to be off?

RS-Chevy-SS

Inside of rad looks a lil corroded but not too bad. EBL says temp is about 10* F cooler than the gauge reads.

RS-Chevy-SS

Re-did the plug and sealant last night and let it marinate over night. Came out, fired it up, still seaped.

When to autozone and bought a bronze NPT plug instead of the black steel plug which i think was npt.

Applied some sealant, replaced the plug, fired it up with no cure time. No leaks or seepage. Possible had the wrong thread type. Who knows.

Fast355

iTrader: (2)

The exhaust side of the head is a little hotter than the water neck reading.

That being said it sounds like eliminating the bypass did help cooling to an extent if it stopped creeping hotter.

The weird part is at idle the additional power of the L30 should not be causing you a heating issue. However that being said if your timing or idle mixture is not quite right it could run hot. Have you tried advancing the idle timing a 2-4* to see what happens? My 350 idled around 24-26* stock and the older TBI engines were 16-20* at idle.

Your idle a/c being 60*F also seems like it could use some additional airflow.

RS-Chevy-SS

Well I tested this theory again right now. Didn't seem to help cooling much. The car crept up to 220ish on the gauge slowly. Would cool a few degrees when rolling.

Sat idling at 220 for about 10 minutes. It didnt get hotter or cool down. Just stayed at 220. EBL verified this but EBL shows 210 when the gauges shows 220.

Do I just need more fan? Its weird that the car cooled fine with the LO3. Now not so much.

Spaceboy1980

iTrader: (6)

Cooling problems when sitting still is fan or radiator. An inefficient radiator is more likely to do it all the time. I wish you were closer, I actually have a spare I would let you try. I think your taurus fan may be making more noise but not more CFM. I have read it is two speeds, perhaps you are only wired in to turn on low speed. What temp is your fan switch?

ETA check this out:

https://www.thirdgen.org/forums/cool...ml#post4617475

RS-Chevy-SS

Yeah so its around 5600 on full speed. The stock fan is ~1200-1500 according to my research. The biggest design issue is the lack of a shroud on our stock electric fans.

In stock form, the fan pulls air from all around the fan except for the radiator. The taurus fan I have is much better but I did a bad job of trimming the shroud to fit back in 07. There's a good size chunk missing at the top. Still worlds better than stock though.

RS-Chevy-SS

Interesting observation to add to this. I've noticed that i can now run with no fan at highway. Before with the bypass, I still needed to run the fan in extreme circumstances. Such as greater than 100*F ambient temp with AC on at highway, or on a hill in hot ambient.

This is even with the brand new lower air dam i installed in june ish.

Now, i can run the car hard on the freeway with AC on and no fan. It will approach 210F but then immediately start cooling back down. Still though, as soon as I hit city driving i hit the fan, and it begins its slow steady climb to 210-215.

Thoughts Fast, RF?

RBob

iTrader: (1)

This is going to sound crazy, but the thermostat is bad. I went through this once before dirt existed. The coolant temperature would go up way above the thermostat opening temperature.

Then suddenly crash back down to the thermostat temperature. The plunger was hanging up and required a bunch more pressure then it was supposed to (to open).

RBob.

RS-Chevy-SS

Wouldn't that issue be evident at all temps though? At night there are zero issues. Temp cycles up to therm temp and back down.

snake006

I have a question I hope some one can anwser my LO3 in my trans am, I had my Holley carb put on it well had to buy a electric fuel pump bec my old motor used a mechanical one well my new Electric one keeps going out on me for some reason iv already changed out two in a month n it's bad again think it's a 10psi pump why is it going bad and how can I fix my probably plz help.

Spaceboy1980

iTrader: (6)

Well it's a cheap part and very easy to replace. You could also toss a 180 in there while you are at it but you would want to change your fan switch if you do.

RS-Chevy-SS

Fan switch is bypassed. It already has a new 180 from the swap. Seriously doubt that's it. Doesn't have any issues in cooler weather

Fast355

iTrader: (2)

You know RBob might be onto something. My Express suddenly started running hot yesterday. A little diagnostic work tells me that the radiator is full and the fans screaming, at idle warmed up the upper hose is scalding as the ngine was 230-240*F but the cool side radiator tank is cool to the touch. When I start driving the coolant temp plummets down to 215 and stays even at 80 mph. Thermostat is sticking or only opening partially and the higher rpm is increasing the flow to cool it. Going to try a new thermostat this afternoon when I get off. Will keep you posted.

Fast355

iTrader: (2)

New Murray 180*F thermostat from O'reillys and its running188-194*F in 97*F with the a/c blasting.



Also worth mentioning, my A/C high side service valve started leaking and leaked all my Diflorethane out and not having any on hand on the Sunday I fixed it, I charged it from my 30# R134a cylinder I have. Been swealtering with 48-50*F a/c at idle ever since, blows 35-38*F on the highway though.

RS-Chevy-SS

Which one did you go with? The stock 3.99 one of the Murray plus with a bigger valve for more flow?

Fast355

iTrader: (2)

Yea the standard,stock replacement version, not the ultra or whatever they call it.

RS-Chevy-SS

My only reservation is that I can turn AC off in hot ambient air of 90F+ and have no issue. As soon as AC comes on it starts warming up. Then at night with AC on in about 80F it will idle all day long with fan only.

This brings me back to an airflow issue. Im just not seeing the consistency to show a bad T-Stat. Am i missing something here fast?

Fast355

iTrader: (2)

Maybe so its hard to say for sure. That being said, did you not say it was running warm at 210*F going down the highway? At 70 mph the fan should not even be running and steady airflow should be keeping it near the thermostat rating.

On the Express I found a secondary issue. With the thermostat issue, hot running all summer and recent overheating, I ended up burning up a cooling fan motor in my Tahoe E-fan assembly (It had popped the fuse a few times recently and seemed to be turning a little slow, then siezed up entirely). So I tried something new to keep it cool. I removed the electric fans and went back with a mechanical setup after trimming my shroud to clear a 21" very aggressively pitched Duramax diesel fan. Drove it around yesterday evening in 99*F temps. It now stays around 185*F while driving. With the a/c blasting at idle, stuck in the traffic from a wreck it started creeping up to 190~192*F on my HPTuners datalog. Suddenly there was a screeching shudder under the hood and the fan clutch engaged. Within 10-15 seconds the fan had returned to idle and the coolant leveled out at 183-185*F again. The Duramax fan reminds me of a school bus or a semi truck when it is engaged at slow speeds. The best part is the clutch rarely engages compared to the stock fan setup, the idle cooling is much better and the a/c blows as cold if not colder than with the E-fans. Was cooling 44-48*F at idle last night once it cooled down.

Duramax vs Stock 99 Suburban tow package fan.


Duramax fan installed on L31

RS-Chevy-SS

No, the car stays cool in hot ambient on the highway with AC blowing so long as I don't have the grill buried behind a big truck or anything. If I'm in open highway it's fine, in heavy highway runs a little warm but still lower than city.

Man I don't think I have enough motor to run that fan. Not even sure it would clear in the engine bay. Dad has a 2500HD GMC with the duramax. Thing sounds like a freight train when the fan engages.

I also don't have a mechanical shroud, probably wouldn't be effective without it correct?

Also wondering if my fan motor is getting tired. Doesn't quite seem as loud as before. It has never been replaced since I got the Taurus fan and I'm sure its the stock motor that came on whatever taurus it was bolted to

Fast355

iTrader: (2)

HAHA....Wasn't really suggesting for you to try to convert to a mechanical fan and clutch, just stating I had more than one issue going on and a weak/dying fan motor was one of them.

It does sound like a freight train when it kicks in and draws some power off the 350, but even being 99*F yesterday evening it only kicked in briefly a couple of times. Moves so much air even when it is declutched and idling, it really didn't have to lock in the clutch so much.

Spaceboy1980

iTrader: (6)

Did you ever get the cooling hammered out?

RS-Chevy-SS

No, been driving it around once a week. Been really busy with work and such. Also been having cooler weather here in CA so might be too late. Really wanna get some LS1 fans in it though.

morgsie

iTrader: (1)

mechanical fans are always better for heavy vehicles or towing.

Fast355

iTrader: (2)

Not for cooling at idle and slow speeds they aren't. It definately runs warmer with the Duramax fan at idle and my a/c is not as cold. That being said as soon as you get up to 1,000-1,500 rpm the mechanical fan starts pulling a decent volume of air and it cools down nicely and the ac gets ice cold.

RS, just though I would mention I recently swapped to a smaller orifice tube from a 99 Cadillac Seville, leaving the rear expansion valve alone. In conjunction with the Duramax fan and a proper charge of R134a it is reaching 42*F at idle and going down the road the compressor is cycling out at 30*F from the vents. Its been 90-95*F and the a/c is gettting so cold it will hurt your knuckles. I find myself constantly having to switch from recirculate to outside air and not running more than about the 2nd notch on the fan speed.

The head pressure at idle increased about 10-15 psi, but the suction side dropped about the same. Seems to be making a huge difference in my dual system. Highway cooling feels about the same, maybe slightly better.

RS-Chevy-SS

Very tempting but to swap that out requires "evacuating" the system right? Seems like a pain.

Fast355

iTrader: (2)

Yes it does along with vacuuming the system down for about 1 hour after the fact and recharging.

I discovered the orifice tube by accident changing the orifice tube in the 99 Suburban when I changed the compressor.

RS-Chevy-SS

Well now that its been a few days, how is it?

Fast355

iTrader: (2)

Still blowing ICE cold. Idle cooling seems better, highway cooling seems to still be great, granted we have not had a day hotter than about 95*F in the last week or so. Humidity however has been killer. Knocking on wood, I think I finally found and repaired all the small leaks in the system. Practically every o-ring has been replaced, the a/c manifold hose last summer, the front evaporator 3 years ago, the rear expansion valve 3 years ago. The aftermarket Sanyo style compressor on it is about 8 years old and was starting to make some noise. When I had everything apart, I tossed 2 oz of ICE 32 Sytnthetic Oil Booster and 2oz PAG100 into it. Compressor is nearly silent again like when it was new.

RS-Chevy-SS

Yeah see mine is too new to break it all down again. Only been 3 months. The other night at the wash I had the AC running. Actually froze beads of condensation on the lines, then unfroze when it kicked off.

Spaceboy1980

iTrader: (6)

Man, you guys are running AC still and I'm reaching for my jacket, lol.

Fast355

iTrader: (2)

I did not have a choice, I broke the low pressure switch on the back of the compressor resealing a leaky valve cover. While it was apart I decided to see if I could make the R134a work acceptably rather than going back to R152a.