Any ideas on why my Series 60 runs so hot?

belfert · December 31, 2018, 04:02:11 PM

I replaced the water pump, thermostat, and radiator core on my bus with Series 60 in the first year or two I had the bus due to very serious overheating issues. I took the radiator to a radiator shop and they said it had a lot of pinholes and someone had put leak stop in it. They offered to close off the bad tubes, but I chose a new core instead.

Since I replaced all that stuff normal temperature runs 195 to 200. I use high quality Zerex HD antifreeze and I always make sure it is full of coolant. This past fall the high temperature alert in the DDEC tripped several times at over 215 degrees. It never got hot enough to trip the high temp shutdown. We stopped for about two hours and checked a bunch of stuff like making sure the air filter was not plugged and also verified the air intake was clear.

It seems like I should be running at least ten degrees cooler and am looking for ideas on what to check.

Bill Gerrie · December 31, 2018, 04:37:09 PM

If you ever recore the rad again use a dimpled tube core. They are up to 30% more efficient. I had overheat issues a long time ago after changing the exhaust system. Turned out there was too much back pressure. You may want to have your back pressure checked. I don't know what the figure is for a series 60 but it should be in the book under specs. You may also want to check your thermostat. Even if new they can be defective. A friend of mine has 95 Dina with a series 60 and an 8 speed. No issues at all with temp or anything else. Also check your fan to see if it is coming to full speed when required. The thermostatic coupling may be defective.

luvrbus · December 31, 2018, 07:28:06 PM

Low turbo boost will heat a series 60 check the boost pressure

belfert · December 31, 2018, 07:53:54 PM

The turbo boost PSI seems low to me at 14 to 15, but someone here said that is normal on an 11.1 Series 60.

blue_goose · January 01, 2019, 07:30:00 AM

Is 14 to 15 the max boost or is that what you are getting running down the road.
Jack

belfert · January 01, 2019, 07:49:25 AM

I don't recall for sure. I think that is max PSI.

When I first got the bus there was a bird nest inside the air intake partially plugging it. As a temporary fix I removed the rubber elbow going into the air filter. I later cleaned out the bird nest and put 1/2" hardware cloth over the intake to stop birds and animals. I checked the intake for any obstructions on my last trip and nothing found. Bryce Gaston had warned me about the intake possibly being plugged. He had seen a Dina where the intake piping collapsed as the intake was completely plugged. In that case I believe he said the engine had to be rebuilt.

thomasinnv · January 01, 2019, 07:58:00 AM

14 to 15 running on flat to very mild grade is fine, but you should see mid to high twenties under load full throttle. With the cooling system in good shape you should not be able to overheat the 11.1 no matter how hard you push it, unless someone did some reprogramming and really pushed the power up. When I was still running the 11.1 the highest it ever ran on a long hard pull on a hot day was 205 to 207, which is right where the thermostat reaches full open. After I had the radiator cleaned out it would run steady between about 195 and 202 no matter what I threw at it.

Now that I have the 12.7 running at 1550/470 things are a little different but thats to be expected.

thomasinnv · January 01, 2019, 08:05:00 AM

Brian sorry, temporary brain fart. I don't know why I was thinking you had a D series like me. Obviously we don't have the same cooling system as I originally thought, but even so the 11.1 should be a difficult one to get hot unless the cooling system is not up to snuff. You definately need to find out why your boost is low, that will cause the overheating. Disconnect the wastegate and see if it goes up to normal. You may have a turbo in your future. How is the power? Does it seem a little light?

belfert · January 01, 2019, 08:21:00 AM

I have no idea if power is light or not. I expect a 40,000 lb brick going down the road isn't going to be the fastest thing on the road. Temperature has been an issue basically since I got the bus, but it was slightly worse this past trip. Cooling a four stroke is not supposed to be much of an issue compared to a two stroke.

I'm not opposed to doing something with the turbo if that is really the issue. They aren't terribly expensive as far as I know.

thomasinnv · January 01, 2019, 08:34:51 AM

Brian, how are you reading boost pressure?

belfert · January 01, 2019, 09:32:43 AM

Reading turbo PSI off Silverleaf VMSpc.

thomasinnv · January 01, 2019, 11:16:57 AM

I would think it would be pretty accurate then. You need to take it for a run and verify what kinda boost you are getting under full load full throttle. Then we can see what way you need to go from there.

chessie4905 · January 01, 2019, 11:35:20 AM

Make sure you aren't getting bubbles in coolant overflow tank, warmed up.

belfert · January 01, 2019, 12:12:31 PM

Dina doesn't have a sight glass into the expansion tank. The lack of sight glass can cause problems determining the correct level of coolant in the tank. I can't fill the tank 100% due to the design (which I don't want anyhow), but if I fill it up as much as I can excess coolant will spray out from under the fill cap.

I won't take the bus out for a run probably until May unless I end up going to Texas in February.

luvrbus · January 01, 2019, 12:54:34 PM

Test the inter cooler sounds like it is leaking 25+ lbs should be normal under a load or it will heat didn't you bump it up to 370 hp ?