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1987_345 · 04-06-2009, 11:06 AM

Is there anyone running a 454 Chev in their motorhome. I recently acquired mine and am a little concerned with the water temp being too high

345bill · 04-06-2009, 11:38 AM

Hello, welcome to the forums. From what I've read here some other 345's w/454 seem to run a little warm also. On ours, within the last year I installed new radiator (USA made), engine water pump, thermostat, hoses, fan clutch, exc. and I would have liked it to run a little cooler than it does. It never has gotten HOT though. Another thing to consider is how are you determining the actual temp? I'm not so sure how accurate the original temp. guages are. Another factor in our situation is that we live in the desert so higher temp's are expected, especially in HOT summer months. I hope you end up enjoying your new MH as much as we enjoy ours.

swinginping · 04-06-2009, 11:45 AM

I have an 89 with a 454 in mine, which i think is plenty of power but as your concern read a few posts about the high temps. However, I agree with bill I'm not so sure the original gauges are correct. I put one of the radiator caps with a thermometer and have used an infared laser thermometer and cannot find anything that reaches 200 degrees or up near what the gauge is telling me. I've only had my engine fans actually kick in once and that was the middle of summer of a decent pull.

ptero · 04-06-2009, 01:52 PM

My '91 350 ('90 chassis) w/ 454 indicates hot as well. I just recored the rad, new fan clutch, tune up, etc, and it continues to indicate +/- 220. The mech checked it with a separate gauge, and that read the same as the dash gauge, indicating the dash gauge is correct. He also said that the location where the sensor pickup was placed (next to a combustion chamber in the middle on the driver side) could be producing a higher temperature reading than at other locations of the system, due to that cylinder possibly running a little hotter than the others, causing the higher reading. He wondered about that placement, but said to just keep an eye on it to see if, how, and when it changes.

(Not too comforting when I'm on I-10 and I-8 this summer - with a Jeep Liberty CRD toad - if the needle starts moving to the right). As an afterthought, he said he had noticed other (than Airstream) motorhomes with the 454 on P30 series chassis also sometimes ran hot.

1987_345 · 04-07-2009, 06:52 AM

Thank-you so much. So I guess its alright to show 200-220. I wonder at what temperature the "HOT" warning light would come on? I just installed a US Gear overdrive and had hoped it would drop the temp a little

1987_345 · 04-07-2009, 07:05 AM

Sorry, but I also meant to ask you how the tow vehicle thing works out for you. I am considering a jeep wrangler as a tow vehicle, but with the suggested 2000lb tow weight limit in the manual, I am a little apprehensive. Have you had any trouble?

swinginping · 04-07-2009, 09:50 AM

Sorry to butt in here, but there are a few posts on how to modify/strengthen the tow hitches, I believe one person pulls a race car and enclosed trailer with theirs.

1987_345 · 04-07-2009, 01:29 PM

Don't mention it, glad to have you. I think the hitch is stout enough, being a cat 3 and all, I was actually referring to weather or not the bus had enough power to pull it or stop it. I figured the owners manual says 2000lbs is the limit. I just wondered why

Poprivet · 04-07-2009, 03:39 PM

My 1990 250 runs hotter than I would like when running up hill and I have noticed in the 30K + miles I have driven it, the situation seems to get worse. I find that if I slow down and downshift it cools right down.
I plan on doing a good flush before going out this season.

I wonder if the water pump looses efficiency over time? Any thoughts here?? My experience with water pumps is that the seal fails but they don't pump less over time but then how would you know??

345bill · 04-07-2009, 04:44 PM

Quote:

Originally Posted by Pop Rivet

My 1990 250 runs hotter than I would like when running up hill and I have noticed in the 30K + miles I have driven it, the situation seems to get worse. I find that if I slow down and downshift it cools right down.
I plan on doing a good flush before going out this season.

I wonder if the water pump looses efficiency over time? Any thoughts here?? My experience with water pumps is that the seal fails but they don't pump less over time but then how would you know??

Pop Rivet- My above post may have been misleading on why I changed the water pump. You are exactly correct concerning the seal as that's what started leaking which led to changing the pump. I agree that even with a bad seal it should pump the same, but it seems like I remember when you have a seal failure a bearing failure is usually lurking. Everything else along the way was changed simply because it's such a bear to get at all of it. I was hopeing for a little cooler running temp's mainly due to the new radiator, which actually helped by about 10 degrees, all in all though my cooling system was probably not that bad of shape, but now I have the peace of mind knowing that I SHOULDN'T have any cooling system failures in near future, knock on wood.

Poprivet · 04-07-2009, 05:32 PM

Quote:

Originally Posted by 345bill

Pop Rivet- but now I have the peace of mind knowing that I SHOULDN'T have any cooling system failures in near future, knock on wood.

Ahh - peace of mind - I have probably spent big $$$ and $$ just to achieve that comfort zone when I'm on the road. Some call it "preventive maintenance" Whatever, it works for me!

1987_345 · 04-08-2009, 06:43 AM

I am somewhat mechanically inclined espesially on the pre computer controlled vehicles and I have never heard of a water pump losing effectiveness. I think possibly for a variety of reasons the thermostat might become faulty over time. I've been a ford man for years and haven't owned a GM product since the 80's. For the last 15 years i've been driving a diesel and it runs really cool. The fans rarely come on and when they do it cools it right down suggesting the front of the radiator is too congested with other things to allow for proper air flow. Since we can't remove the a/c condensor maybe we can relocate the trans cooler and oil cooler or even somehow change the sensor for the fans so they come on sooner. thanks for your help, this site is truely a blessing!

swinginping · 04-08-2009, 02:30 PM

I had a 94 camaro with the 5.7 which was a great motor for me, had nearly 200k on it when i sold it but it ran hot whenever in traffic or warmer weather. The fans didnt even kick in until like 227 or somethign way up there, similar to the AS's, always seems like chevys run hot or are intended to to me, so i simply ran a manual fan switch which i fused in the actual fan relay fuse... however, I dont think it'd be as easy to find on the AS's... but im thinking about doing that to mine wherever i can find an empty spot. If you have a cat 3 hitch already mustve already been modified because most of the stock hitches i know of were simply fixed in with the bumper and frame, which is why the manual says 2k, mine was modded and has a cat 5 but the metal they used as the hitch hangers/brackets was low quality and is rusting out so im not sure how much i actually trust it.

Robfike · 04-17-2009, 09:35 AM

We had the hitch rebuilt by Dan's hitch in Elkhart, IN. We now have a 10,000# tow limit with a weight distributing hitch. We tow a race trailer that is 7000# loaded. The 345 tows it with no problems at all.
On the temp question...Last January I replaced my water pump due to coolant starting to leak from the weep hole. Since we were about to leave for Florida, I did not want to take a chance. With the old pump and the new one, my normal temperature is about 190. But now with the new pump, if we idle for about 8 minutes, the temp goes up and the "Hot" light comes on. If I rev the engine, or drive off, it cools back down. Go figure.
Rob

deltatango · 07-04-2009, 09:58 AM

I have an 82, 280. It has a new crate engine, new radiator, new clutch fan, all new engine stuff. It cools great at idle. It gets warm at speed. (approx 210) Let it idle again and its down to 170.

I know it's making more residual heat at speed so it has to dump more heat. But there is the cooling fan shroud that looks to me like it is blocking the natural ram air at speed thereby making the engine run hot.

Take off shroud. More air at speed. Better cooling.

Anyone?

345bill · 07-05-2009, 08:22 AM

Quote:

Originally Posted by deltatango

I have an 82, 280. It has a new crate engine, new radiator, new clutch fan, all new engine stuff. It cools great at idle. It gets warm at speed. (approx 210) Let it idle again and its down to 170.

I know it's making more residual heat at speed so it has to dump more heat. But there is the cooling fan shroud that looks to me like it is blocking the natural ram air at speed thereby making the engine run hot.

Take off shroud. More air at speed. Better cooling.

Anyone?

deltatango- concerning removing shroud: we have a 1970 GMC 'Jimmy', 350 small block. I tried to drive it across town (once) without the shroud on (to wrecking yard to get new shroud) and it ran wayyy to hot where I had to stop more than once to let it cool down. Fortunately I was able to find one there but had the same trouble getting home until I could put in on. Once it was in place, no more running hot problem. I would think the shroud directs the cool air that the fan pulls thru the radiator to the front of engine. Just my 2cents.

However, on our motorhomes, it sure would open up access to everything if that shroud wasn't there blocking it all but I think you would be creating new problems.

choctawmel · 07-05-2009, 12:58 PM

my 'silver bullet' runs upwards of 220 degrees too. I installed a electric fan oil cooler under the bump in a large air dam, It runs 220 degrees. I moved the tranny cooler down under the bumper, it runs 220 degree. I run the dash A/C or don't run the dash A/C and it runs 220 degrees. I had the radiator roded and cleaned, it runs 220 degrees. If it's 50 degrees out, it runs 220 degree.
The fan clutch will kick in on most hills, which is a big drain on the engine power.
Wonder if someone makes a shroud with hinged doors that would open when the air flow warranted it. I've seen small cars with doors on the cooling shrouds.
mel

eubank · 07-05-2009, 01:17 PM

You know, I wonder if some Redline Water Wetter might help out the situation a bit. I used to use it in our old MG back when we lived in hot country.

Red Line Oil: Coolants and Others

Lynn

Mike Leary · 07-05-2009, 02:12 PM

They run hot, so what? I've never heard of too many of them blowing up; the plus is you can wrap your dinner in foil and put it on the manifolds, be ready in a half hour.

1987_345 · 07-05-2009, 03:10 PM

I agree. I think you would probably be creating more problems by removing the shroud. It would definately run hot at idle. I read a post which suggested that the anti freeze be no more than 50/50. Mine was a full 100%, and when I reduced it down to 50% it did run cooler. Go figure. By the way my problem of running out of gas turned out to be a faulty new filter at the carb. In the mean time I have replaced ALL of the flexible lines from the tank and blew out the soild lines. My mechanic suggested we leave out the filter at the carb since the gas has already been through 3 filters by the time it gets to the carb. Running great. Sorry it took so long, anf thanks for all of your help. Kenneth