345 Motorhome overheating.

[Myrtle lynn]

Ok. Need ideas. Took the 87 345 out this weekend coming back on I 85 in GA. I was going about 65 mph after 40 minutes of driving in 90* weather she started to light up HOT. I was cresting hill turned dash air off coasted down to 50 mph and temp dropped to about 220* kept going since temp dropped. This is the first time I took it out since new radiator, new ac condenser. I also had a new electronic thermostat control installed to have fans turn on at a lower temperature. I know these thing run hot but not that hot right? I bought it in Indiana 8 months ago drove it home it heated up then, but I was going up mountain in TN and I still had old antifreeze and old radiator and fans that came on only when it lights up HOT. I plan on taking it to AK in august. What do I need to do? Done all that I know to do. Suggestions?

[HowieE]

When was the last time you had the radiator roded and cored. That should be done every couple of years.

You may be interested in what is wedged in the fins. I back flush my radiator and AC condenser often with a wand that uses air and water.

This will show you what you can expect on the outside.
HowieE

[Myrtle lynn]

Originally Posted by HowieE

When was the last time you had the radiator roded and cored. That should be done every couple of years.

You may be interested in what is wedged in the fins. I back flush my radiator and AC condenser often with a wand that uses air and water.

This will show you what you can expect on the outside.
HowieE

Just had it done. $1500 later. New ac condenser as well due to first people knocking off fitting while removing radiator.

[HowieE]

If you are good with the radiator the next thing to check is the thermostat. Remove the stat an place it in a can of water on the stove and heat it up. The stat should be fully open just as you see small bubbles forming and before the water boils.

If both radiator and stat are good you may want to look at the head gaskets. Is there any evidence of steam coming from the tailpipe after the truck is fully warmed up, at least 20 mins down the road.

I just saw your location. I lucked into Akins Ford in Winder Ga a few years back. That is the only shop I would ever recommend. There truck shop should be able to help you and I doubt they will brake off any AC connection while working on the rig.

[Myrtle lynn]

Originally Posted by HowieE

If you are good with the radiator the next thing to check is the thermostat. Remove the stat an place it in a can of water on the stove and heat it up. The stat should be fully open just as you see small bubbles forming and before the water boils.

If both radiator and stat are good you may want to look at the head gaskets. Is there any evidence of steam coming from the tailpipe after the truck is fully warmed up, at least 20 mins down the road.

I just saw your location. I lucked into Akins Ford in Winder Ga a few years back. That is the only shop I would ever recommend. There truck shop should be able to help you and I doubt they will brake off any AC connection while working on the rig.

Haven't noticed any steam coming from the tailpipes, but I really haven't looked. Aikens is a great dealership. I have bought many cars from them. Very reputable in town. I will try the thermostat trick. I haven't replaced it yet so I am going to do that tomorrow. I will test the old one though. Any recommendations on a thermostat?

[HowieE]

Even if the specs call for it don't go above 180 degrees F.

[cooperhawk]

You need to check if there is really pressure when running. Water pressure I mean. We had replaced the coolant lines running back to the water heater from the engine and one had rubbed on a bracket enough that it was leaking pressure. I assume your pressure cap is good on the radiator but if it's leaking pressure somewhere else it will run warm.

[Keyair]

What a pain after everything you have done!

Ok, lets back up here....
It was getting hot before you did the radiator, so we have to assume that its NOT the radiator..

Make sure that it IS actually running hot...
Test the temp of the top hose with an IR non contact Thermometer and see if it is about the same as what the gauge is reading... Its is possible that the gauge is wrong or the sender is failing... or a wiring problem..

This leaves the usual suspects as:

1/ Airflow thru the radiator:
A/ Check the Viscous Coupling is working... they fail... lots!
B/ Make sure just for fun, that the fan itself is the correct rotation 5 or 7 blade(my '87 3/4T BBC powered Suburban has a huge 7 blade as part of the towing package).
C/ Make sure the fan is spinning the correct way to PULL air.. (dependant on year and belt config, the fans can be reverse rotation, or even mistakenly mounted backwards!)
D/ Is the Fan shroud still fitted? If not the fan is not pulling air efficiently thru the radiator..

Now, there has been a lot of talk here about the Viscous coupling being the holy grail for cooling the BBC... but my 345 is fitted with a solid mounted "Flex fan", and whilst I dont like them and worried about it, it never allowed my motor over 220deg climbing up to Flagstaff at full throttle in 90 deg weather. I did in fact deliberatly push the M/H on this section to see what the temps did...
Pic here..


2/ Coolant flow and temp:
A/ Check the Radiator cap is correct pressure and the system is sealed and pressurised... if its leaking pressure the coolant boils!
B/ Check the thermostat is correct and opening.
c/ Water pump maybe failing, but normally they leak, but I have heard of impellor failure due to corrosion..

Edit..
I posted this while others were posting... so a little repeating what they said!

[Keyair]

More thoughts..
On a light throttle on the flat at 60mph what was the general temp reading?
You say you had the dash A/C on?
How was the A/C temp?

[Keyair]

Good info here:
http://www.airforums.com/forums/f159...eat-62152.html

[345bill]

All good tips posted above but if I was in your situation I'd definatelly do what Keyair suggested in post #8 first.
Make sure the hot signal your seeing is actual hot and not a false signal, especially considering what work has already been performed.
Easy enough to verify then you'll for sure know what direction to start troubleshooting.

[Myrtle lynn]

Originally Posted by Keyair

What a pain after everything you have done!

Ok, lets back up here....
It was getting hot before you did the radiator, so we have to assume that its NOT the radiator..

Make sure that it IS actually running hot...
Test the temp of the top hose with an IR non contact Thermometer and see if it is about the same as what the gauge is reading... Its is possible that the gauge is wrong or the sender is failing... or a wiring problem..

This leaves the usual suspects as:

1/ Airflow thru the radiator:
A/ Check the Viscous Coupling is working... they fail... lots!
B/ Make sure just for fun, that the fan itself is the correct rotation 5 or 7 blade(my '87 3/4T BBC powered Suburban has a huge 7 blade as part of the towing package).
C/ Make sure the fan is spinning the correct way to PULL air.. (dependant on year and belt config, the fans can be reverse rotation, or even mistakenly mounted backwards!)
D/ Is the Fan shroud still fitted? If not the fan is not pulling air efficiently thru the radiator..

Now, there has been a lot of talk here about the Viscous coupling being the holy grail for cooling the BBC... but my 345 is fitted with a solid mounted "Flex fan", and whilst I dont like them and worried about it, it never allowed my motor over 220deg climbing up to Flagstaff at full throttle in 90 deg weather. I did in fact deliberatly push the M/H on this section to see what the temps did...
Pic here..

2/ Coolant flow and temp:
A/ Check the Radiator cap is correct pressure and the system is sealed and pressurised... if its leaking pressure the coolant boils!
B/ Check the thermostat is correct and opening.
c/ Water pump maybe failing, but normally they leak, but I have heard of impellor failure due to corrosion..

Edit..
I posted this while others were posting... so a little repeating what they said!

What a pain is right. It ran hot when I picked it up, but figured I haven't had chance to go over it completely. Ok going to harbor freight tomorrow getting an IR thermometer. Step one. This morning before reading this thread now I called my mechanic and told him about it running hot. He said sounds like fan clutch. He Explained the whole thing about how they work and that a good quality one is extremely important, how they get weak after a while ... I did look back at the records from the first shops work that was done and the thermostat was replaced. After reading all this I will have a lot to do. Ha. What is the viscous coupling? Location? It seems like in some of the threads people recommend getting rid of the hot water coolant lines. I really don't ever for see a need for it to get hot going down the road. What about removing all the smog stuff? Keep in mind I am going to do all of the above these were just some questions I had. I have a trip to AK this August and really wanted to take it. Hope I can get some faith in it. I am going to keep working on my new to me 34' AS to have as a back up. Really can't beat a 2011 ford F250 king ranch with heated/AC seats. Lol

[Myrtle lynn]

Originally Posted by Keyair

More thoughts..
On a light throttle on the flat at 60mph what was the general temp reading?
You say you had the dash A/C on?
How was the A/C temp?

On a flat at about 55 it was just under 220. It went down when I turned off AC. The AC blew very cold.

[HowieE]

220 on the flat with the AC on is high.

The viscus coupling is the thermostatic fan coupling. I have never heard of one going bad but I guess it is possible to burn the clutch out if it was used frequently. If the coupling engages you should hear a noticeable change in the engine noise as the fan is engaged at direct drive.

If you say it was running hot just after you picked it up odds are they screwed up on something. Check the fan orientation and then check to make sure it is turning in the right direction. The serpentine belt on some engines can be routed to cause the rotation to be wrong. A quite and easy check by looking just as the engine is turned off and watch the coast down of the fan. Check the thermostat as even new ones can be bad or some can be put in upside down and thus the bulb never see the hot water to cause it to open.

Any auto parts store should have a radiator cap pressure test kit. Take it off and make a trip to one. While a bad cap will not cause overheating, it prevents premature boil over by raising the boiling point do to the pressure, it still a good thing to check at this point.

If you can see directly into the radiator while the cap is off a test of the pump would be to have someone rev the engine once warm. The liquid level on the radiator should be pulled down just a bit as the engine revs up. Pumps generally last about 80,000 miles. However I have seen a Dodge pump complete loose the impeller fins from dissolving. This however is not an over night thing. But looking at a 15,000 mile trip to Alaska you might want to change it now. If you do there are high capacity pumps that are rated above 130 GPM.

[Splitrock]

I chased an overheating car once and all that was wrong was a bad radiator cap.

[Myrtle lynn]

Originally Posted by HowieE

220 on the flat with the AC on is high.

The viscus coupling is the thermostatic fan coupling. I have never heard of one going bad but I guess it is possible to burn the clutch out if it was used frequently. If the coupling engages you should hear a noticeable change in the engine noise as the fan is engaged at direct drive.

If you say it was running hot just after you picked it up odds are they screwed up on something. Check the fan orientation and then check to make sure it is turning in the right direction. The serpentine belt on some engines can be routed to cause the rotation to be wrong. A quite and easy check by looking just as the engine is turned off and watch the coast down of the fan. Check the thermostat as even new ones can be bad or some can be put in upside down and thus the bulb never see the hot water to cause it to open.

Any auto parts store should have a radiator cap pressure test kit. Take it off and make a trip to one. While a bad cap will not cause overheating, it prevents premature boil over by raising the boiling point do to the pressure, it still a good thing to check at this point.

If you can see directly into the radiator while the cap is off a test of the pump would be to have someone rev the engine once warm. The liquid level on the radiator should be pulled down just a bit as the engine revs up. Pumps generally last about 80,000 miles. However I have seen a Dodge pump complete loose the impeller fins from dissolving. This however is not an over night thing. But looking at a 15,000 mile trip to Alaska you might want to change it now. If you do there are high capacity pumps that are rated above 130 GPM.

My Moho is 1987 345 with 56k miles on it. Not really used that much. Ran hot after I picked it up in Indiana from the po and it had sat for some time before that drive. This past weekend was really the first test drive since I got it back from mechanic after months and months. It does have new radiator cap along with new thermostat. In the spare parts the po gave me was a water pump. Oh sorry I am driving to Arkansas, not Alaska. Lol. I am going to look in the paperwork from the po. They are very detailed and a lot has been done. It's just so I have an idea.

[Splitrock]

I had a collapsed bottom hose on my delivery truck once. It looked fine from the outside. That overheated. That baffled us for quite awhile.

[Myrtle lynn]

Originally Posted by Splitrock

I chased an overheating car once and all that was wrong was a bad radiator cap.

Thank you. Already been changed. I had a lot of stuff done to this thing.

[Myrtle lynn]

Originally Posted by Splitrock

I had a collapsed bottom hose on my delivery truck once. It looked fine from the outside. That overheated. That baffled us for quite awhile.

All hoses have been replaced, but I will make sure.

[Mike Leary]

Somewhere back there, I saw a post about "sender and gauge"; I'd go there first, though we all know how hot a 454 can get.