914/V8 Fan Operation, Conversion Cooling Options

[tyler]

Can you conversion guys tell me how your electric fans operate and if you've modified the air dam?
Put in my 15.5x28 Griffin radiator with 944 Turbo fans on a shroud. Crusin at 70 on the freeway the temp starts at 170 for 6 miles and creeps up to 195 when the fans come on and bring it back to 170. This continues to cycle like this both on the freeway and around town. I'm using a 160 Tsat until the cooling system is done. I ran with the lid off so I know the cuts in the wells are ok. So I figure I'm either blocking the airflow with the fans/shroud or the air dam need to channel the air in somehow. It doesn't seem to me like the temp should cycle like this. I'd like to hear how yours run.
Thanks,
Tyler
'70 914/350/4 webers

[John2kx]

Tyler,

It does not sound like you have a real overheating problem since your temps. are well within normal range, but I admire your desire to smooth things out. You may want to burp the system a few times to ensure all air is removed. This will help the temperature cycling if air is present.

A 180F thermostat may keep temps more consistant as well. Of course anytime you break into the cooling system you will have to spend several days going through the burping procedure.

A kinked hose can cause similar problems. Double check the inlet hose to water pump as well as the two smaller hoses from pump to inlet at engine.

What temps. are you using to turn fans on and off? The attached pic shows what RH uses and should show the on and off trip points. Another factor may be where you have your sensor located. The optimum location is at the radiator with sensor actually making contact with coolant as opposed to being attached to a hose or radiator surface.

John

[914GT]

Tyler,

John is right. If you go with a 180 thermostat the temperature will stabilize better as it regulates at the higher temperature. If your temp sender is located in the head as opposed to the intake manifold next to the thermostat, you will also see more temp variations. I'm running a radiator sensor that fits between the fins and it has been working fine. Here lately with daytime temps around 105F, my engine temp goes up to 180 in a few minutes and once I'm on the highway for awhile it creeps up to 195. I have the fans kick on at a little lower temperature than really necessary, and let the thermostat do the regulation.

[neo914-6]

related question, the tstat of choice is Mr Gasket "High Flow". I just bought one marked as "Balance HP" 180 degree #4364. The speed shop was unaware of a "High Flow" type. Did I get the right one?

[MikeP]

I've drilled a few small holes around the tstat to allow a small ammount of consistant water flow through the system, seems to help with the cycling.

[bondo]

How big are your hoses? I've heard having large hoses can cause this problem because it takes too long for the coolant to get up to the radiator and back. Probably not THE problem, but it could be a contributor.

[tyler]

Thanks for the comments - I did drill a hole in the tsat and I installed and air bleed at the top of the radiator. Also the overflow tank is functioning, so I'm convinced I have all the air out (you're right this did take awhile). Since the fans pull the temp down fine, I'm pretty sure it's an air flow issue. I read engine temp on the gage (sensor in manifold near tstat) and have a sensor threaded in to the radiator tank which by adjustable switch is set for the fans to go on when the engine temp is almost 200.

[bondo]

QUOTE (tyler @ Jul 22 2005, 10:56 AM)

Thanks for the comments - I did drill a hole in the tsat and I installed and air bleed at the top of the radiator. Also the overflow tank is functioning, so I'm convinced I have all the air out (you're right this did take awhile). Since the fans pull the temp down fine, I'm pretty sure it's an air flow issue. I read engine temp on the gage (sensor in manifold near tstat) and have a sensor threaded in to the radiator tank which by adjustable switch is set for the fans to go on when the engine temp is almost 200.

Oh, I see what you mean (I should read posts more carefully). Here's a thought.. if the fans unmount relatively easily, you could take them off, and cruise at 70 and see how hot it gets. If it still gets over 195, it can't be the fans. The firebird I took my V8 out of had a fan shroud with 2 fans, and on the areas not covered by fans were these openings with rubber flaps that would blow open at speed, but when the fans came on at low speed they'd get sucked closed. If it is the fans you could devise something like that.

[914GT]

QUOTE (MikeP @ Jul 22 2005, 10:31 AM)

I've drilled a few small holes around the tstat to allow a small ammount of consistant water flow through the system, seems to help with the cycling.

I did this too, but I found the engine took too long to get up to temp in the wintertime. I went back to a plain old thermostat with no holes.

[tyler]

Hoses are 1" from engine and 1-1/4" back to pump. You're right - I plan to move the fans and shroud back to make sure I'm not blocking airflow out of the radiator. Next I'll put the cover back on the airspace in front of the radiator to see if that directs air into, instead of over the radiator (I've been running all open with the hood off). I've heard of those rubber flaps, which sounds like a good idea which I'll try if it turns out to be rear blockage but it seems like most installations are a full shroud.

[John2kx]

QUOTE (Neo914-6 @ Jul 22 2005, 07:42 AM)

related question, the tstat of choice is Mr Gasket "High Flow". I just bought one marked as "Balance HP" 180 degree #4364. The speed shop was unaware of a "High Flow" type. Did I get the right one?

Felix,

You have the correct t-stat.

John

[ewdysar]

ALL air entering the trunk through your front openings should be ducted to the radiator. If the air has any way to get around the core, it will go that way rather than do any cooling (path of least resistance and all...). On the RH setup the top plate from the front wall to the top of the radiator is critical. If your set up is open, that was my impression after your last post, the fans are the only thing forcing air through the core, leading to cooling with the fans on and much less while they're off.

Eric

[John2kx]

QUOTE (tyler @ Jul 22 2005, 10:56 AM)

I plan to move the fans and shroud back to make sure I'm not blocking airflow out of the radiator. Next I'll put the cover back on the airspace in front of the radiator to see if that directs air into, instead of over the radiator (I've been running all open with the hood off).

Putting the cover back on shroud is highly advised and should help a lot when on the road. Too much air is being allowed to escape through the opening and not "through" radiator. The right t-stat (180F) and setting the fans to come on earlier should fine tune the system in all areas of operation (traffic and open road).

Note: the Renegade switch is set to come on at 180F and off at 171F. Your system is playing catch up with the activation switch set at 200F.

I'd also do some further testing to really heat soak engine and cooling system. I define a real test as logging 30 or so miles of open road driving in 90+F weather with a occasion journey in stop and go traffic.

I really like the idea of holes (three 1/8" equally spaced) in the t-stat since the "by pass" is omitted with the remote water pump. The holes in t-stat eliminate dead heading of pump when starting from cold as well as provides a path for air to escape from "other side" of cooling system when being filled. Also assists in removal of air when performing the burping procedure.

John

[pjhaun]

QUOTE (John2kx @ Jul 22 2005, 06:32 AM)

Tyler, It does not sound like you have a real overheating problem since your temps. are well within normal range, but I admire your desire to smooth things out. You may want to burp the system a few times to ensure all air is removed. This will help the temperature cycling if air is present. A 180F thermostat may keep temps more consistant as well. Of course anytime you break into the cooling system you will have to spend several days going through the burping procedure. A kinked hose can cause similar problems. Double check the inlet hose to water pump as well as the two smaller hoses from pump to inlet at engine. What temps. are you using to turn fans on and off? The attached pic shows what RH uses and should show the on and off trip points. Another factor may be where you have your sensor located. The optimum location is at the radiator with sensor actually making contact with coolant as opposed to being attached to a hose or radiator surface. John

John:

Could you possibly tell me the size of the thermo switch? Is it 3/8" pipe threads?

Thank You!!!!
Phillip J. Haun
Oak Harbor, Wa.

[John2kx]

Phillip,

I'm going on memory, but think it was more like 1/2". To be sure, you could check with Renegade.

John

[LS6/914]

Is there adequite air flow volume exiting the the radiator through the inner fender well or deck lid ?

[914GT]

Do they make those screw-in thermo-switches adjustable? I like mine because it has an adjustment control I mounted on the fan shroud. In the winter I set the temp a little higher.

[tyler]

I have a top cover and there is complete sealing to avoid recirculation. After looking at the Renegade pics, I did some testing and found that the side plates to channel the airflow in (removing turblence) and a little air dam in front to force the air up towards the radiator make a major difference. Ran for ~30 miles (about 80 outside)right on 185, fans never came on. I'd like to see pics of what anyone runs for an air dam since I just used a short piece of sheet metal and there must be something nicer looking and more efficient. I didn't see anything in the Renegade pics.

[tyler]

I have a sensor threaded into the radiator for setting the adjustment on the fans and just set them for an engine temperature (read next to the thermostat) of 200.
With the Renegade sensor (goes in the radiator?) turning the fans on at 180, I don't understand how they would ever shut off with a 180 TSAT. Am I missing something?

[914GT]

The fans would probably shut off if the water temp cools down enough to cause the thermostat to start closing off. Be interested seeing a picture of your air dam under the car. I was thinking off adding something like that at the rear of my intake opening.