Hello,
I have a 1994 Winnebago Brave motor home mounted on a 1993 Chevy P30 chassis.
It has a 7.4 L 454 Chevrolet V8 and automatic Tranny. It has 35K miles and runs great but has sat for long periods of time. My problem is it overheats when climbing hills ( around 230 F -240 F ) and runs around 210 F much of the time on level roadway.This is in 85 to 95 degree weather.
I am starting to pull the radiator for cleaning and rodding out and was advised to change the fan clutch also. As you may suspect, it is quite an operation to remove the radiator so I only want to attempt this only once and may even replace the water pump along with the belts and hoses. My question is, would I be better off to replace the belt driven fan with an electric puller fan instead of buying a new heavy duty fan clutch? It already has a 16" pusher fan in front of the A/C condenser. Cost is not a problem, I just want the best cooling system I can get this first time around. I also wouldn't mind freeing up a couple of horse power.
Any advice will be appreciated......THX...J-Doug

Hi Doug,

If it came with just a fan clutch it really should be enough. There's a big difference in quality with these things. If the one there used to work get that exact one. Otherwise go OE or at least Hayden's best. They really don't last all that long. At three years old they are noticeably losing pulling power. Yes they suck HP away when working hard but you won't have an engine if it's cooking all the time either??

If it needs help get an electric set up to boost it but I don't think you should try to eliminate it for just electric unless there really is one that is that powerful. Remember the energy of direct power loss with the belt is noticed but the power the alternator has to come up with is the same - it just spreads it out more so you may not notice.

I know these are a PITA so I would go for a new not rebuilt water pump. I wouldn't for general automotives but this really works hard. I've done a bit of marine work and lots of Chev 454s are used. They do make marine ones but it could be hard to match up. The only real difference is for marine they use brass and stainless parts in the same housing. You know - some are salt water cooled.

None of it can be any better than the ability of the radiator. That should have come with a maxed out radiator and must stay that way.

I have had problems in the last year with quality of the clutches in plain cars never mind the load that you must deal with,

T
Tom Greenleaf - MetroWest Boston - USA
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http://www.autoacsystems.com/tomgreenleaf/

Oooops: To add........ the vehicle may suggest it but if you lower the anti-freeze concentration care fully to -20 or even -10 degrees F. it will help - I know the yachts mandate that. It also means less anti-corrosion help so it really should be changed every year. The heat transfer ability of anti-freeze is terrible. Plain water is much better but you can't get away with that so don't do that. Something to consider if dealing with extremes,

T
Tom Greenleaf - MetroWest Boston - USA
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http://www.autoacsystems.com/tomgreenleaf/

Thanks Tom, You have answered my question very well. I did have some reservations on going with Electric only and decided to do research first. Your right , If the OE was good enough too start with, it should be now also. I sure don't want a "redo" in three years.
I will go with a new OE water pump and fan parts along with new belts and hoses. I may go electric on a oil cooler and /or transmission cooler.....But then again, OE should have been well enough there too J-Doug

Thanks Again Tom,
I appreciate the advice on the Anti Freeze. I had never thought about that. In fact I thought the more the better... Glad to know better. I have found a product ,I believe, at Camper World that is suppose to lower and maintain the radiator temp quite a bit. I would want to do much research on that before I trusted it.
I'm trying to get the radiator out without opening up the A/C condenser lines and move it out of the way as I have no way to reclaim the R12 at home. It looks like I will have enough slack in the lines the way they installed the A/C system but I have a vacuum pump and a new Dryer if not. I will just have to find some place to reclaim the R12.....
Again, Thanks......J-Doug

More: Do your best not to have to open the A/C. You'll have trouble finding a place that will still reclaim R-12 as it's getting rare now. It also is contaminated by so many folks just buying R-134a kits and mixing it up that it can wreck everything in the recovery tank or sealers jamn up the equipment so who the heck wants to mess with it anymore?? Nothing will or could ever work better. If you have to and find a place do cover the open lines right away - don't let air in. Replace any O rings - lube with baby oil is ok - no kidding!

The heat exchange value of coolant: Water = 1 (one) That means it takes 1 calorie of energy to heat or cool 1 gram of water (H2O) 1 degree Fahranheit. Anti-freeze by itself might be .65 (maybe less!) so it's like losing 35% of radiator space. Mixed 50/50 you lose let's say 12.5% and when you lessen from 50% you are getting back at what was lost. Not sold here but in climates where it never freezes there is an anti-corrosive "coolant" that probably can beat plain water. Highly salted water would but "duh" not a good idea. Ask about the coolant at the RV place. Get a real opinion not just the ads on containers.

Sorry for the science class.....

T
Tom Greenleaf - MetroWest Boston - USA
_________________________________________

http://www.autoacsystems.com/tomgreenleaf/

Tom,
Just a follow up on this thread...I tried to remove the radiator without opening the A/C lines but wasn't able to due to the space involved. I cracked a line in the process so I removed the condenser and repaired the crack. Have gone back with new dryer and freon. All seems well.
My radiator was really plugged up even with only 35 K miles. I guess the idle months over the years take their toll. I had it cleaned but to no avail. It opened up several leaks and I had to have a new core. I feel better about a new radiator anyway. The weather is still too cool to see the effects of extreme heat but I think the radiator was the only problem I had.
As bad as it was, I feel that the clutch fan and water pump had to be working really well to keep it cooling on level terrain...
Thanks again for your Advice,
J-Doug

Hi again,

Things sound good except for the A/C getting broken. Just how did you fix a crack in something? This is light years more sensitive to leaks than a cooling system and most shops aren't equipped to repair these things.

What are your intentions with that when the time comes? Are you considering R-134a refrigerant? Can you get good R-12 for a recharge? Not much virgin product around and frankly any alternative stinks especially for this application.

I do suggest you unplug the compressor until you are ready to work on it as it can click on with requesting defrost and without refrigerant in the system it WILL harm the compressor as the refrigerant carries the oil that lubes the compressor.

Note: It should know better by lack of pressure to click on but it could with just heat of the engine on the lines and parts heating up just air in the system but only for a second if all is well with it.

Let us know what you want to do with that. The only thing you might do if expecting many weeks more of cold is to perhaps evacuate the system and leave it either pre-charged or in a state of vacuum till later. It would help your new drier to last longer and work better. Ask away - you can't rent tools and pump to do that for free with 100% security deposit if you don't have anything to work with,

T
Tom Greenleaf - MetroWest Boston - USA
_________________________________________

http://www.autoacsystems.com/tomgreenleaf/

Tom,
The crack was in an aluminum tube of which I was able to replace. I have completed the 609 automotive A/C course and have my certificate so I have a fair amount of R12 cans. They are getting more expensive at around $30 each but I found a bargain while shopping. I found three 14oz cans for $50.00 + shipping.
I also have a fairly good CFM vacuum pump that I used to pull down and hold a vacuum for a couple of days before I recharged the system.
Your right on about the R12 system being the better of the systems. This system was made for Winnebago's by SCF Frigette and still carry some parts and dryers so I hope to keep it going as long as needed.
J-Doug

That's a deal for the 14oz cans. For a while you could bet about a $buck a peice for those! Count the ounces as my luck is that once those cans are pierced you can't save them for very long,

T
Tom Greenleaf - MetroWest Boston - USA
_________________________________________

http://www.autoacsystems.com/tomgreenleaf/

Tom,
I have a follow up question on this......
I live in Texas at an altitude of 3500 feet and there fore can only pull a 26 inch vacuum on my gauges as opposed to 29.9 at sea level. I can leave this vacuum on there for 48 hours and it leaks down to around 22 inches of vacuum in that 2 day span. Do you think this is an excessive leak that should be pursued or can it be expected to leak down some?
All books I have read on evacuation the system only
stated to wait a few minutes to see if it leaked down, then pull a perfect vacuum according to the altitude and hold it for 30 minutes before recharging the system.
I had put on a new dryer but didn't have any R-12 oil to add to it. I'm keeping the system in a vacuum
state till my oil arrives.
Thanks, J-Doug

True about the Hg reading at altitude - ok with that. I don't like the leakdown. Fair chance it's your gauges leaking or connection. Check on that as it should hold.

I forget exactly but atmospheric pressure is I think 17.6 psi. That means just 17lbs of force gets thru the leak. The R-12 must stay sealed tight up to about 400psi.

For now, perhaps try again and recheck you gauges and how they seal. Other trick it to pressure up with nitrogen and some R-22 and check for leaks with the static pressure alone which should be in psi about what the ambient temp is. That is allowed to vent when done.

Most shops would wait 1/2 hour or so and call it good. 48 hours is a long time. Funny also is that some leaks will leak in vacuum but not in pressure - especially shaft seals for some reason.

Certainly best to find any leak before wasting any of the GOLD R-12! Electronic leak sniffers, soapy water, whatever you can do to prevent starting off with a leak.


Keep us posted,

T
Tom Greenleaf - MetroWest Boston - USA
_________________________________________

http://www.autoacsystems.com/tomgreenleaf/