Running below op temp

[cranetruck]

There is a lot of talk about potential problems with dry starts and poor filtration lately, but what about running an engine below operating temp? If someone made an engine pre heater, we'd probably "know" all about it too.

So, what about runninng an engine at 120-140°F for an hour or so, what are the consequences?

 

[Armada]

Good question. I think a couple would be... Combustion would not be optimal resulting in decreased engine efficiency and accelerated contamination of engine oil.

 

[No.2Diesel]

By constantly operating at low water temps, the piston rings probably don't expand enough to conform to the shape of the cylinder wall increasing wear and blow-by. I have made a plywood radiator blocker like Bjorn's and keep it behind the grill all year. When temperatures go below 30°F the entire core is blocked off to keep temps at 185°F-200°F I have purchased and installed a ZeroStart block heater just like Rattlehead with amazing results.

You can certainly feel the difference in power and driveability running your Multifuel at 120°F as oppossed to 185°F

 

[ken]

I hope the effects arn't too bad. When driving off road. Mine rarley gets above 160. In the winter it runs about 120. But the only thing i have to go off of is the gauge. witch could be wrong. When running down the road it stays pretty close to 180 winter or summer.

 

[Barrman]

I can't remember where I saw this, but I think it was in some kind of street rod type article about thermostat selection. I also don't have a copy, so I am going to paraphrase from memory.

A cast iron engine is designed to operate at a temperature that allows proper clearances to develop between all the moving parts, oil to flow, coolant to cool and the least amount of wear on the parts to happen. Most American V8's have this magic temperature around 172 degrees coolant temp. More than 10 degrees cooler and proper clearances don't develop causing wear to rings, cylinder bores, valve train components and valve guides. Not to mention air/fuel mixture airation problems in carburated engines. More than 10 degrees warmer and the magic clearance/wear window gets shut again.

Because the rate of wear is less at 180-190 than at 150-170, most engines came with a 180 degree thermostat. With the thinking that 100% load would be rare and at least several cylinders would be cooler than others and right in the middle of the optimal wear pattern.

That is about all the article I can remember. What it means to me is you want 160 plus in the engine before a big load or for long run times.

Now, newer alloy blocks, head and other components along with synthetic lubes, coated and treated pistons and stuff changes the thoght process for newer vehicles. But for good old cast iron work horses keep them above 160 and below 190.

Don't forget that the temp gauge is just reading the coolant temp at one end of the head. You really have no idea what each cylinder is operationg at.

This help any or just confuse?

 

[m139h2otruck]

Somewhere in the dim recesses of my brain, I recall seeing a graph of engine wear vs operating temperature over time for car engines. The graph had a very steep curve from low temperature (75-100) up until about 160 or so and then the curve flattened out almost to a zero slope till about 230+/-. This is why over the road trucks (and most all new style computer controlled trucks of any type) have such fancy temperature control shutters, thermostats and fan controls on them. I think the fact that the multis tend to run cold adds to engine wear and may be a factor in the myth of short life for these engines. As I stated in an old post, I have seen a number of different make engines with 15,000 to 35,000 hours on them, still running strong with just normal oil changes, clean air filters and clean fuel.

 

[Pinkie]

I second the mention of the m35 running alot better at 180 then 120. Engines are designed to run at certian temperatures. If your truck is running to low (lower then 160 or so) check your thermostat and make sure its not stuck open, I know mine is. If thats not it create a wind block for the radiator. There was a good write up on how to make one around here somewhere....

 

[willysmd]

Hi All
Try this link and see if it helps with the discussion here.

http://www.carnut.com/ramblin/_cool3.html

 

[alphadeltaromeo]

When I towed the 6ton semi with the 3k dolly the other day...after a really long hill and pushing the deuce hard, it got to 195...that was it. i was happy about that.

 

[SasquatchSanta]

Greetings Fron The Minnesota North Woods,

To find their efficiency, diesels need to have a fire built in them. "Building a fire" doesn't just mean getting them up to an ideal operating temperature of 180 to 190 degrees --- it means achieving a "normalized" temperature.

The LDT465 is a huge chunk of iron to heat up. There is always a huge temperature spread between the fire deck and the bottom of the piston stroke but during cold weather starts, until the engine is THOROUGHLY warmed up, the temps at mid block (mid-stroke) are such that operating expansion and contraction tolerances are completely out of whack.

Before I installed the electric fan and removed the water pump fan my temps wouldn't get above 120 degrees on cold days.

Now, on 10 to 20 degree days, with the water pump fan removed and the electric turned fan off, I have to idle my deuce at least 30 minutes to warm it up to 180 degrees. Even after it's warmed up to 180 degrees it still doesn't run right for another 20 to 30 minutes.

My engine has very little crankcase breather blow-by but during idling warm-ups I have noticeable crankcase odor. Without the water pump fan or an electric fan pushing air through the engine compartment blow-by odors are more noticeable. I've since installed an extended breather host.

I've also noticed that during warm-ups the engine wet-stacks therefore even after everything gets up to a normalized operating temperature the engine needs to be driven long enough to blow the soot our of it.

In short, I not only think its "REALLY" hard on Multi-Fuels to drive them before they have warmed up to 180 BUT ALSO to drive them very hard until optimal engine heat has had a chance to disipate and "Normalize" throughout the engine.

Also, when I crank Rosie up on a cold day I make it a point to drive at least 20 miles before shutting down.