Bus running too cool...

[Scott & Heather]

Have driven coach from Arcadia to Virginia so far. It has run perfectly. 21 psi of boost, 70 psi oil pressure, pulls hard and strong like a 500hp fresh rebuild should. I'm still breaking it in. Will be doing my first oil change on the new engine in Pennsylvania swapping out the 30 weight break in oil for the 40w delvac per Leid Diesel instructions. I have only one issue and Leid told me not to worry about it but I still do:

The coach is running really cool. As in, when we left Florida yesterday it was in the mid 80°'s and the highest temp she could muster was 175° running around 70mph. Today we're further north and high temps are in the 70°s and it only mustered the high 160°'s unless I pushed it 70mph or more. I tried to stick to around 65 mph with one short stint to 83 mph while passing. I did remove the transmission fluid heat exchanger and install a Hayden trans cooler with twin cooling fans on it. So that took a heat load off the engine coolant for sure, but I'm really concerned if I'm driving the coach in any weather in the 50's or below that I'll need to block off a radiator. I have brand new twin 180° tstats installed and Leid Diesel confirmed this when I called and asked them about it. But it just isn't building heat. How concerned should I be?

[Ed Hackenbruch]

My bus ran at 175, never bothered me....if it started running hotter then i kept a close eye on it. Heat will kill it just about faster than anything......except running out of oil.  

[RichardEntrekin]

Scott,

Sorry I don't remember the details of your setup, what is the source for the temp readout? Is the signal coming from the engine computer DDEC? Or from an added sensor to the engine? The point being to check the coolant temperature independently to verify the reading at the cockpit is accurate.

[luvrbus]

170 degrees is minimum for a 92,you may need to switch to full closing thermostats,what is the temp on the Allison they don't like cold temps either   

[CrabbyMilton]

Different vehicle same issue for me. My '04 GRAND MARQUIS has a bad thermostat that where the temp. is almost always near the cold section according to the gauge. Better to be too cold than hot all things being equal. However, it may effect you MPG, since at least a FORD transmission, it doesn't go into lockup unless the engine is above a certain temp. A bit louder too since it runs a bit faster. I think the ALLSON behaves that way too.

[Utahclaimjumper]

You wont be sorry when the ambient temps are 90 and climbing a long grade..>>>Dan

[windtrader]

Classic symptom that thermostats are not working properly. I'm no expert but assume a bus without circulating water will register over 180. Otherwise, radiator shutters are supposed to take care of very cool ambient temps, right?

[luvrbus]

Classic symptom that thermostats are not working properly. I'm no expert but assume a bus without circulating water will register over 180. Otherwise, radiator shutters are supposed to take care of very cool ambient temps, right?

Not the case the 92 series and 71 use a "Weir" type thermostat his cooling system is in great shape and the rebuilder has the engine well tuned or he would generate more heat.I always carried a full blocking thermostat for my 8v92 in extreme cold weather I would install it on 1 head to get the temperature up he doesn't have a problem ,let him cherish the moment it will change in July,fan clutches replaced shutters years ago 
   

[richard5933]

Isn't the part of the reason many buses were equipped with Webasto heaters? So the coolant would be hot enough to produce heat inside the bus?

[Scott & Heather]

The webastos weren't used to heat the coolant of a running coach. Rather to heat the coolant on a cold day so the bus would start, or to provide quicker heat for the interior.  I will ask Leid about the full closing tstats cliff. To answer the earlier question, I'm getting my readings from the DDEC II computer and they are exactly matching the readings from both the mechanical engine bay coolant temp gauge and the dash gauge. Running too cool.

[luvrbus]

Scott diesel fired boilers like Webasto were used to warm the temps up on a running bus too ,the DL with the series 60 really needed the help in cold temperatures 

[niles500]

Even when the t-stats are closed the bypass is still circulating coolant, sounds like your got a solid rebuild, be happy

[muldoonman]

Well Scott I would let you have a little heat coming Off my turned up 8V92TA if I could. It has me watching that gauge here in Texas when temp is running over a hundred pulling my tow car. Hope you get it figured out. Know you will.

[Scott & Heather]

Cliff, 4 strokes, yes they need help sometimes to build heat but I've never ever heard of someone using a webasto on a warm two stroke to keep the coolant warm other than for starting purposes. I have no idea how this will play out this winter. But we will see. I may have to reinstall shutters.

[chessie4905]

I didn't know you have shutters for it. Just reinstall.