Overheating in 30’ 1993 454

[Streamerden]

I have a 1993 p 30 Chevrolet Legacy/ land yacht. It has a brand new crate engine from the previous owner, 94,000 miles. Last summer in ambient temperatures over 80° I had routine high temperature , Pushing the red. I have since replaced the thermostat, fan clutch, and radiator. I also discovered the factory single electric fan was pulling not pushing air so I have to buy a new electric fan apparatus to cooperate with the fan clutch. This winter I drove it to Arizona from the north. Ambient temperatures never went over 75° yet I still found I had to be extremely careful of the temperature. It is never boiled over. I have use the infrared gun on the lines which correlate with my gauge.

Presuming our gauges are all accurate , What are the other land yacht and Legacy motor homes experiencing for operating temperature? Aside from long mountain climbs in 95° weather, and aside from driving 40 mph what solutions have you found work? Where does your temp gauge sit? The only thing I have left to replace is the water pump. I routinely only drive 54 to 60 miles an hour, no toad.

[davejay]

Hey,
What I found on our MH was that the gage is faulty. I put a Fitech fuel injection in and it comes with a small monitoring screen. Anyway, the gage says we're running at 220-240 degrees, but the Fitech sensor, which is mounted right at the thermostat, says it's running at 177 degrees and steady. So, I think you may have a gage problem. At an idle, my gage would run at 260 degrees, it never overheated, that's what makes me think it's a gage problem. When we took it out on its maiden run last summer, even with a bad engine running 13 pounds of oil pressure at 60 mph, it never got above 185.
I'd put a water pump on it if it's an old one. The seals get hard. They're so cheap, it's worth doing, belts too. Hope this helps. DJ

[GCinSC2]

I've never worked or even seen the engine compartment on a rig like yours but the IR temp gun should be a big help.

How about something hopefully simple temp reading of coolant going into radiator and temp reading coming out.

[uraljohn]

Couple of suggestions from an old school drag racer that ran a few 454's back in the day. If you can contact PO, ask them why a replacement crate engine was installed. Did they have overheating problems? Where was the crate engine sourced? If not from a known engine re-manufacturer (Jasper comes to mind) it may have some problems contributing to overheat problem (cylinder bores enlarged to much resulting in thin cylinder walls). Is the engine timing set properly? Is there to much total timing advance dialed into the ignition system? Are the radiator hoses the correct ones? Lower hose should have a wire spring inside of it to prevent hose from collapsing resulting in poor coolant flow. If a new crate engine was installed, why wasn't a new water pump installed at that time? Buy a high performance thermostat and test it before installing it to make sure it opens at correct temp (drilling 4 small 1/8" holes in the small flange area of the thermostat is an old trick to increase coolant flow, this will allow engine to warm up properly but let more coolant flow after thermostat opens). Contact "Jegs" or "Summit" to purchase a high performance water pump. (these are companies that supply racing parts). Is the fan shroud in place to insure all air is being properly funneled through radiator to insure maximum radiator efficiency? Is the exhaust system restricted in any way? Is the muffler old? It can look fine from the outside but be rusted inside resulting in obstructed flow that will contribute to higher engine temps. Is there sufficient venting of the engine compartment to insure the hot air can escape? High under hood temperatures can contribute to overheating. Just a couple of things off the top of my head that you can check. Hope this helps. Happy travels.

[uraljohn]

If your motorhome has Catalytic Convertors as part of the exhaust system (to control emissions) they may be partially plugged up. At 100k miles on a 454 that is toting around a motorhome they may/probably need replaced. There are several sources for these. OEM parts will cost a bunch. The aftermarket can supply replacement convertors for much less cost. Now, I would never suggest something that is illegal, but you may be shocked just how much better that 454 would perform with a custom bent dual exhaust system with some Magnaflow or Flowmaster mufflers in place and no catalytic convertors. Just sayin.

[Mike1997]

My Landyacht is a diesel so it may not be a good comparison but my temp gage rarely goes over 200. Its usually around 170-180. On the highway I cruise at 65mph. Only times its ever gone over 200 was in mountains south of Colorado Springs and I was towing a Jeep Grand Cherokee. I tend to worry more about going downhill to fast vs up hill to slow Thank goodness for jake brakes!!

[92landyacht]

My 36' LY with a 454 routinely runs above center and will approach the red area on the gauge on hot days. This is especially true if I'm climbing inclines. It was much worse until I replace the radiator. Prior to that it would overheat just idling. With that said, the temp sensor is located near the hottest part of the engine in the head near the exhaust manifold. Like others have mentioned, I'd check the temp sensor and do a quick check with an infrared gauge (cheap at Harbor Freight) and verify what's actually happening.

[Captain Paul]

I’m wondering if you were able to resolve your engine temperature issues? When I bought my motorhome the engine temperature gauge would only go up to 140°. I change the thermostat to make sure that it was not stuck open... no change. On my 1998 MH there are two engine temperature sensors. One that goes to the computer (located right below the thermostat and the upper radiator hose) and a separate one on the drivers side of the block that goes to the dashboard gauge. I replace the engine temperature sensor and once again when it warmed up it only read 140°. After lots of help from a neighbor and troubleshooting, we have determined that the sensor is designed for a digital gauge but on my airstream we have an analog gauge. I have installed an aftermarket gauge which is much more accurate than the gauge in the dash. I put the new gauge sensor into the port on the side of the block. I have also ordered a new temperature sensor that should be compatible with my dashboard gauge. I’m going to add that to the upper radiator hose. That way I’ll have a back up and I really don’t like to have gauges that are non-functioning. I will test it this next week when I get the new gauge and let you know what the temperature readings are as well as list the part numbers.

[Streamerden]

Thank you everyone for your suggestions. I have not used the unit since this thread. Captain Paul, what kind of chassis is in your unit?

[Captain Paul]

I have a 1998 Chevrolet P 30.

[vintageracer]

Get a NEW modern design large internal tube style aluminum radiator.

IF as the OP says the previous owner did not replace the water pump when they installed the new crate engine you can bet you fanny they did NOT clean, replace or service the radiator in any form or fashion.

You should ALWAYS install a new water pump and radiator whenever you install a new engine. In most instances with most engine rebuilder's or crate engine replacements failure to do so will void your warranty.

[NavyCorpsman]

Transmission good? Are the coolers / condenser in front of the radiator full of crud?

[Captain Paul]

Update on my RV:
The Engine temperature sensor that was in the vehicle that did not work is an ACD 12554253. This is the sensor that is listed for this engine but it only seems to work with a digital gage. I replace this sensor with a MaxTow double vision 280° sensor that I purchased on Amazon. Then I added a water temperature adapter to the top radiator hose and installed a Carquest WT611 sensor to the dash gage This seems to be working perfectly. Both are 1/8” thread size so if you do you replace the sensor on the side of the block you will need an adapter for 1/2” thread.

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