Your alternator has just burned up and it’s only a year old. You grumble a bit and march off to the parts counter for a replacement. You dutifully install the new one – “an exact match to the original,” the parts guy said – and get on with life. That one will probably burn up about a year from now too. And chances are, you’re not the only one this is happening to.
At issue here are component failures related to higher-than-expected underhood
temperatures found in trucks running EGR engines.
The issue of underhood heat is significant enough to have prompted the TMC (Technology and Maintenance Council of the American Trucking Associations) to convene a Study Group Session at its annual meeting in February  to look into the matter. Reps from several of the affected parts and components manufacturers made presentations on the effects of under-hood heat, clearly
demonstrating that heat is a significant issue with all makes of post-2002 engines
in pretty well all truck brands.
Session moderator Jim Winsor, executive editor of Heavy Duty Trucking magazine, noted that hoses, for example, that should last a lifetime are failing within two years – one example presented failed at less than 150,000 miles due to excessive heat. Winsor says he has seen examples of seal failures on power-steering pumps, failed belt tensioners, fan clutch troubles, and many other
problems with air lines, windshield-washer bottles, etc.
Before panic sets in, it’s important to note that while heat is affecting almost all
trucks built after the emissions regulations went into effect, trucks that operate in hotter regions of the continent, such as the U.S. southwest and southeast, are experiencing more failures than trucks based in Maine, North Dakota, and
Minnesota. Presumably we can include Canadian trucks in that group as well, but
with the heat of summer approaching, it’s prudent to sound the warning bell at this point.
Hoods and engine compartments that were optimized for external aerodynamics and 400-hp engines now contain larger powerplants that produce a lot more heat.
And we’ve now got to deal with the heat created by the EGR paraphernalia.
Generally speaking, air passing through the radiator, charge air-cooler, and the
A/C condenser – all behind the grille – is entering the engine compartment at a
higher temperature than was previously the case. We’ve created a perfect
environment for cooking engine components.
Jim LeClaire, manager of field service and warranty for Horton, Inc., says what
was expected to be a minor issue has become a major one. “Underhood
temperatures have risen more than we expected,” he said at the TMC heat-management session. “We’re seeing early failures or reduced life for many support components due to heat that we never saw before. Lines, hoses, belts,
tensioners, looms, seals, bearings, lubricants, wires, tie downs… It’s a long list.”
How Hot is Hot?
Randy Andis, director of fleet operations for Delco Remy Heavy Duty Systems,
says peak under-hood temperatures are going up, but more troubling are the
higher sustained operating temperatures. In a presentation Andis made at TMC, he noted the following temperatures observed at various points under the hood of several test trucks when the outside temperature was 78°F:
Coolant temp – 205-210°F, up from 180-190°F;
Power-steering reservoir – 225-250°F, up from 140-160°F;
Firewall behind turbo – 220-250°F, up from 180-200°F; and
Firewall on driver’s side – 125°F, up from about 100°F.
“In air-inlet temperature tests at the front of our alternators, for example, we’re seeing temperatures at or above 165°F, 70% of the time. That’s up from about
10% of the time on a pre-’02 engine,” Andis noted.
In terms of peak temperatures at the inlet, Andis says 200°F was almost unheard of in 1999. By ’02, temperatures in excess of 200°F were recorded about 6% of the time the engine was operating. Peak temperatures are climbing above 230°F.
You can’t turn off the EGR and you can’t run with the hood open, but there are a
few things owners can do to minimize the negative effects of excessive temperatures. The worst circumstance is the fast shutdown, especially after a hard pull. Radiated heat from the turbo or other EGR components can literally cook any hoses located near those components. Always allow three to five minutes of cool-down time before shutting down after working the engine.
When conducting routine PM inspections, watch for weeping seals and wet areas
around any fluid connector, especially on the exhaust side of the engine compartment. That could be a warning of an imminent failure. Check for deformed
hoses and airlines sitting near a heat source.
Consider shortening your PM intervals. What worked a few years ago may not work now, and won’t tomorrow. Coolant loses its additives more rapidly under high temperatures, as will oil. Sample and analyze fluids more frequently until
you’re comfortable with the protection.
Several of the presenters at the TMC session suggested removing the inner fender guards to promote better under-hood air flow. That may create noise issues, so check with your service manager before you strip them off.
The trends in recent power-steering system designs has been to shrink the
reservoirs and run shorter hoses, but Richard Petrut, senior account manager at
power-steering supplier R H Sheppard Co., cautions that can reduce the heat-transfer capability of the system. He suggests adding a power-steering oil cooler in extreme circumstances, or at least adding some liquid capacity to the system by running longer hoses and where possible, eliminating as many of the 45-and 90-degree fittings from the system. “Each fitting adds back pressure to the
system, and that creates heat,” he says. “The power-steering pump, when it’s full
of hot oil, acts like a big heat sink, and that just bakes the seals.”
And of course, an ounce of prevention is worth a pound of cure: invest in a couple
of spare belts and coolant hoses, especially those located on the hot side of the engine. Failure is more likely than ever before, so you can’t go wrong in carrying a few spares.
LeClaire suggests owners check for service bulletins on their vehicles, and stay in touch with their dealers on the issue. As well, he suggests networking with other owners doing business under the same operating conditions to see if they are
experiencing similar problems. And when spec’ing replacement parts, make sure
you’re buying the most recent product incarnations as original specs may not be
up to the heat challenges.
Alone in a Crowd
Presenters at the TMC heat-management study group session stressed that these issues are common to all makes of trucks and brands of engines.
Owner-operators’ trucks could be the worst off, in fact, given that owner-ops often
spec larger engines than fleets do – because more power equals more heat.
It’s tough to see failure trends when you’ve only got one truck to look after. What
may appear to an owner-operator as an isolated problem may actually be
happening to a large number of other trucks as well. Knowing in advance that heat
issues are arising should put you in a better position to deal with them. If you work
for a large fleet, talk with the maintenance manager about the heat-related failures
they may be experiencing.
While it’s useful to know that others may be experiencing the same difficulties, that’s not going to solve the problem. Delco-Remy’s Randy Andis says service and warranty concerns will remain an issue between the buyer and the truck
The trouble with warranty on heat-related failures is the proverbial passing of the
buck. OEMs are said to be taking a hard line on the one-year terms of the warranty, passing the claim on to the component manufacturer. They’re flooded with claims, some to the point where warranty losses could become catastrophic.
All that leaves the owner, once again, holding the bag. They’re looking at these
issues on a case-by-case basis.
“Some of the OEMs are coming along on this faster than others,” says Andis. “We’re certainly encouraging customers to take the issue up with the dealer. Owner-operators may have to be more assertive in their claims.”
Chances are you’re not alone with your failed alternator, or hose, or whatever. Don’t let anyone suggest that the problem is an isolated one. Chances are, it’s not.
Heat is creating all sorts of problems under the hood of post-2002 low-emissions
engines. Windshield washer bottles are melting, and there have been reports of
air-brake hoses located close to hot parts doing the same. It’s creating problems
with seals, wire insulation, and lubricant viscosity too. Seals can expand and leak,
lubes become runny and begin to seep past the seals, and wire insulation and wiring looms become brittle, and can even melt in extreme cases.
Hoses are taking a real beating. Rod Ward, director of sales engineering with
hose maker Flexfab LLC, says owners should be taking precautions to protect hoses from the heat by paying careful attention to the routing of the hoses, and by
adding shielding and/or insulating wrap where necessary. “Properly spec’d hoses should last the life of the vehicle, but we’re seeing failures already on some of the first generation EGR-equipped trucks,” Ward says. “The problems with coolant and hydraulic hoses are less obvious because they die from the inside.”
With coolant hoses, watch for a soft, gummy feel to the hose. Thermoset rubber
doesn’t melt, it depolymerizes, meaning its strength will be gone. Thermoplastic hose softens with excess heat, and when cool, they will become rubber-like again but will likely be deformed or sagging. Sagging hoses should be replaced.
Drive belts are seen to be cracking and chipping prematurely partly due to excess heat, and partly because of the extra stress created by more frequent fan cycling.
“On/off fan drives, not long ago, were only asked to be on 10% of the time for
on-highway trucks,” says Vincent Ursini, engine-cooling test manager for Behr
America. “Today’s increased need for A/C condenser cooling, charge-air cooling,
and ECM temperature management require significantly more fan on-time and increased cycles.”
Even power steering systems are taking a hit. Richard Petrut of R H Sheppard
Co. says power steering systems (pumps, reservoirs, and seals) designed for
operating temperatures of 140°F to 160°F are now being exposed to temperatures in the 200°F+ range. “Our seals are good for 235°F,” he says. “But we’re recording temperatures as high as 230°F in some instances. That’s causing leaks and hose failures.”
Spotlight on Engine Heat
TMC is a unique organization in that it promotes dialogue between truck makers, engine makers, component suppliers, and truck users in a non-threatening way.
TMC identifies problems and seeks solutions without pointing fingers. At this
conference [in 2005], where underhood heat was the big issue, presenters from
various component makers spelled out the problems and the challenges.
Going back to the TMC’s Diesel Engine Emissions Summit events that took place
prior to the implementation of the 02/04 EPA standards, the engine makers and OEMs stated repeatedly that underhood temperatures weren’t expected to rise
more than four or five degrees. Component makers, believing existing
componentry was well within the design limits and wouldn’t be threatened by such a modest increase, didn’t turn cartwheels coming up with more robust parts.
It’s clear, listening to the presentations, that heat is more of an issue than anyone
was prepared for. Who’s to blame for dramatically elevated underhood
temperatures – well beyond what was anticipated – wasn’t discussed.
With the 2007 engines about to enter in-service testing, many of those issues will
be coming under very close scrutiny. Nobody is under the illusion that heat won’t
be an issue, and under-hood air movement is now being addressed as a top priority.
TMC presenters offered up some solutions that include putting vents and louvers
in the hoods (testing with one brand of truck revealed a 40°F drop in overall
temperatures with the addition of a hood scoop), radically repackaged cooling
systems, auxiliary fans mounted along the side of the hood to improve air flow,
and others. Other concepts involved careful reconsideration of the shape of the hood and cab to create low-pressure zones around the body to draw heat out from
under the hood. And of course, the component makers are all looking at
improvements to the heat dissipating capabilities of their products. Delco Remy,
for example, has made improvements to the air-induction system at the front end of its alternators, while drilling holes in the casing to improve airflow through the unit.
The problem is far from solved, and it’s expected that heat will become even more of an issue with the ’07s. TMC and all those involved will be hard at it finding solutions. Let’s hope they’re successful.
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