Overheating in stop & go traffic.

[freedombro]

Just made a glorious trip from OKC to LA in my '86 345. Perfect weather (50s/30s), no wind, and 1/2 price gas! I even found a better route, jogging South off I-40 onto I-25 to I-10 to avoid multiple mountain passes. Highly recommend this option to avoid lengthy uphill crawls.

Once I hit LA traffic, the Unleaded Zeppelin began to overheat (hot light on and off depending on speed and engine rpm, no smoke.) It had run a consistent 210 up to that point. The outside temp was in the low 70s. I realized I hadn't heard the roar of the fan clutch the whole trip. I had put slightly more than a gallon of coolant in to top off each morning, though.

The fan clutch and thermostat are only 3 years old...replaced them myself...so I'm wondering if there's another possible issue.

My gut is to replace the radiator, fan clutch, thermostat and hoses in order to have some piece of mind in heavy traffic.

Any thoughts/ideas I should consider before doing so.

My only other concern is that no matter how good she runs I ALWAYS get 5mpg. I would kill to get 7mpg!!!

Any input is greatly appreciated!

Thanks for your time...

-Keith


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[Msmoto]

I think I would determine the source of the leak. If going internally, this is much different than something like a hose, radiator, water pump. A gallon of coolant should be readily seen if leaking out to the atmosphere.

[tevake]

My 345 came to me with two electric fans mounted on the front of the radiator that help in cooling when needed.

How did your two blown out tires work out near Phoenix.

Sounds like you have been having a classic trip.

Cheers Richard

[dznf0g]

Before throwing parts at it, get a pressure tester for the cooling system. Pressure check it stone cold and at full operating temp.(If you're not sure of how to perform the hot test, get it done....there is a scalding risk). A gallon a day is a lot to not see it on the ground, but sometimes intake gaskets leak to the valley and it just boils away. You should smell it though, if that's the case.

Check the underside of your oil fill cap for milky sludge. That would indicate a head gasket, intake gasket leaking into a cylinder or crankcase. Might also indicate a cracked block or head.

[freedombro]

My rig has 2 electric fans, as well. I'll do the pressure tests first. Occasionally, I would see a small amount of fluid leaking out on to the ground, but it wasn't continuous so I just replenished each morning knowing I would confront the issue when I got to LA. No white smoke from exhaust, so I am hoping it's not leaking internally. That would suck.

Richard, as I was loading the 2 blown tires into the rig I noticed one was still fully inflated, even though huge chunks were missing from its sidewall. I decided to remount that one on the tag. It worked. I drove 69 miles @ 45mph to the tire shop, saved $1100 over the Good Sam quote!

Thanks for all the help.

-Keith


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[Waipio Rim]

Have seen more than one thread here on aftermarket fan clutches that did not last long.

Our MPG went from 4-5 to 6-7 when we had the carburetor rebuilt.

[ventport]

If it is blowing out the coolant I would replace the radiator cap first. Then if that doesn't help have it checked for a blown head gasket, or cracked head.

[Forrest]

Try using a "summer" thermostat 160 degree. Also, fan clutches do have a relatively short life span and should be replaced at around 12,000 miles of use. Make sure that your radiator cap has a good seal, otherwise the radiator will be under pressured. A pin hole leak in the radiator not only loses fluid but reduces pressure and allows air to enter the system. You might seal it with an additive. 15 lbs. pressure is normal required pressure for cooling. The coolant pump may not be moving fluid if there is air in the system or perhaps it is not working properly. However, in hot weather under stop and go traffic the engine rpm is often too slow to move enough air. Often, when stopped in traffic I will slip the transmission into neutral and press down on the gas pedal slightly to increase rpm so that the fan moves more air. The alternative to that is what the previous replies stated, to add electric fans.

[PaulnGina]

I agree with everything previously mentioned, but want to add: If you didn't "hear" your fan working, it needs to be replaced. Should be really obvious if it's working like it should. Also, if you have someone who can help you, someone can watch the fan as the engine is stopped. If it free-wheels for a long time after the engine stops, the fan clutch is bad.

[RamblinManGa]

Hi from AZ. . .As my Daddy always told me, do the easy/cheap stuff FIRST ! Verify fans working, do pressure test, replace rad cap, etc, etc. . .always a good idea IMO, good luck, Craig

[bobmiller1]

Sounds to me that your 160 degree thermostat could be the culprit. I would try the factory 12TP1E 192/195 high flow factory recommended GM thermostat available from Rock Auto. The factory fan clutch is also available from Rock Auto, around 200.00 bucks but well worth it. The cooler you run the 454, the less mileage you are going to get. Your coolant loss tells me you have a leak from the weep hole in the water pump. If so, replace with a new Gates. Good luck !

[NavyCorpsman]

Sounds like the fan clutch...does it spin easily? I agree with bobmiller1. Check the water pump. I just replaced mine on the Ford 460 with a Gates pump and it it the best built water pump I have ever seen.

I have used Pusher fans in front of my radiator/oil/tranny/ac condenser with good results. Hayden makes a good setup that includes everything you will need.
Its especially nice when you start over the mountains, or moving slow in traffic on those hot summer days.

[windfallsp]

We had the fan clutch on out 1985 Classic 345 go bad one rainy night in Alabama. After limping to our campground, we had the bad clutch replaced the next day. It went bad in the first 24 hours. (Sometimes they just do.) Had a second new clutch installed and it's been working perfectly for several years now.

To deal with overheating, we've done all the testing suggested by OPs at one time or another. Ultimately, the best fix was a new radiator. It was, after all, almost 30 years old.

With a new radiator, a new exhaust system (including a Banks), a transmission cooler, a super-fan, and the second new fan clutch, the old girl starts on the first try and runs like a Swiss watch. Which is not to say our mileage is that much better than yours, but around here gas prices haven't yet hit bottom. ;-)

[drboyd]

Easy thing to do: Unless you're gonna be in an area below about 20 degrees, run 25% antifreeze instead of 50%, and maybe Redline Water Wetter.

http://www.redlineoil.com/content/fi...ech%20Info.pdf

[guskmg]

If you suspect a cracked cylinder head, warm up the engine, pull all the plugs and spin the starter. If you have a cracked head antifreeze will spew out of the offending cylinder plug hole. Good advice on using the factory thermostat and antifreeze the manufacture recommends. The radiator needs to be at least as large and as many rows of cores as original and clean. When all this is done the heating/cooling system will be in balance. My experience with engines says to do all these things mentioned in this thread. Assure, do not assume, you have a clean radiator, have replace the cap, inspected hoses, clamps,and belt/s, changed out the fan clutch, and replace the water pump. I watched a friend completely overhaul a big block engine for over heating when all that was wrong was a bad radiator cap. He never thought to check the cap. That it why a good pressure test includes a hot and cold engine, and the radiator cap. Don't forget to check out the coolant recovery system.
Good luck in fixing your problem.

[dadstoy]

I would agree that the first thing to do is to solve the missing coolant issue.

If you never hear the fan clutch engage especially if you are running the dash A/C (almost impossible to drive an Airstream motorhome any time of the year without running the dash A/C...LOL), I would agree it probably isn't working. I replaced my fan clutch three times before I got one that worked. First one was from Autozone...didn't work. Second one was twice the price from Napa...didn't work. Then I spent twice the money again and got an original AC Delco fan clutch. It works!

Never try to solve an overheating issue by installing a lower temperature thermostat. The engine, the carburetor and the few vacuum/heater sensor/valves are all designed to run at a certain temperature. The fan clutch is also designed to engage at certain temperature ranges and it will not function properly with a lower temp thermostat.

However, most overheating issues on these old rigs are never solved by replacing thermostats, fan clutches, water pumps etc. it's important that these parts are functioning properly, but the main culprit is the radiator. We all tend to replace all the other parts first simply because of the cost and effort to replace/recore the radiator. I did the same thing.

One of the most significant repair that I have done engine wise was to have my radiator recored. After the recore, all heating issues disappeared and I'm amazed at how consistent the water temp stays in almost all conditions. Second most significant repair was a carb rebuild. I rebuilt my rebuilt quadrajet and the change in performance and gas mileage was significant. On my last trip to Yosemite, I averaged 7.5 mpg on mountain driving and 9 mpg on flat freeway driving!

Last but not least, post some pics of your rig! We all love pics!


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[ROBERTSUNRUS]

Hi, a clogged radiator doesn't dissipate heat; No heat from radiator will cause fan clutch to not work. Replacing a fan clutch that isn't getting enough heat to activate it will make you think that the new one is bad too. In the old days when cars didn't have air conditioners, we would put our hands on the front of the radiator in several places and could find cold spots. From my personal experience, never have a radiator boiled out; It only cleans dirty core tubes. Have your radiator rodded, re-cored, or replaced with a new one. Never put a cooler thermostat in, or a lower pressure cap on.

[dznf0g]

What Robert said.....as well as a radiator which is down on coolant. Not sure a gallon down would be enough to fake out the fan clutch, but maybe.

[FreshAir]

I tow with 2 different 455s, one a '71 Buick and the other a '69 Oldsmobile. I've owned 2 different Buicks a total of 28 years. NEVER have I have gotten much more than 2 years out of a fan clutch. I have left some in longer but I change them out when I am doing extensive towing. I have found that a 160 thermostat works best for me.....as the car runs at 190 degrees anyway. I have installed aftermarket temperature gauges for the coolant and the transmission. Monitoring those temps especially in the mountains tells me when I should exercise caution. As for overheating in traffic that is a good reason to check each of the coolant situations.....leaks, plugged radiator, faulty fan clutch..........

Neil

[Koheleth]

My '86 345 would overheat until I cleaned the outside of the radiator. It had a buildup of crud on about half the engine radiator between it and the a/c condenser where you couldn't see it without taking parts loose. Made a world of difference to have air flowing thru all of the fins.
Neal