Overheating

[mtnedi]

I have a 98 Suburban 2500 Diesel with 100K miles. I had it at the dealer for the 90k/100K ($500) service where they flushed the cooling system. While pulling a camper up a long incline in the Rockies, she started overheating and losing power. This has never happened before - the week prior to this trip, pulled the same trailer up an even longer incline with no problems.

When I complained, they took it back in and said the coolant reservoir needed replacing, charged me another 150 bucks - they also replaced the 2 thermostats. Took the trailer up an incline again and same result - losing power, black smoke, and overheating.

What could these guys have possibly done to cause problems that had never shown up before?

[pannhead]

do you have gauges? loss of power and black smoke... sounds like you're losing boost..they may have bumped the vacuum lines or something...good luck ;)

[rjschoolcraft]

Pannhead is probably right.

These engines are notorious for running hot, though. Check out the thread "Late model cooling mods" on this forum.

I upgraded my 95 to the dual thermostats and HO waterpump that you have, but still had overheating problems until I installed a Kennedy fan clutch. That seems to have fixed my problems (along with an intercooler).

[mtnedi]

thanks - I'll have them check that out. Sure is frustrating.

[ucdavis]

Not sure what the 90/100k "service" consists of beyond flush.
Re: cooling, check with a high power flashlight for bugs n' stuff in the radiator. Lots of folks have sudden overheating in the early to mid summer due to the accumulation hitting critical mass & killing cooling capacity.
The loss of power sounds like something different.

[tanker]

Towing, and the Rockies can both be a creator of heat. Heat will kill almost anything. As stated above, do you have a boost and a pyrometer gauge. If not install them as soon as you can. Why? With gauges you can see what is going on when things are going good, and when you have a problem, they will change, ie; low boost, high exhaust temps.
You did not mention if you have had any performance items installed. So if you are stock, lets look at the basics. There is the possibility that you could have air in the cooling system, but they should know how to bleed the air out prior to sending you on the way. A collapsed lower radiator hose, or a restricted cooling system, bugs and other debri in the radiator core or A/C condenser. Anything in front of the grill? Like bikes, spare tire, anything that would restrict air flow to the radiator. A bad fan clutch, can you hear it engage when it gets warm? Do you get black smoke under acceleration, or on a hard pull? This could be from lack of boost. That could be as simple as stated above, a vacuum hose not connected, or a vacuum leak. The boost solenoid, boost sensor, vacuum actuator diaphram leaking. To much fuel, from a bad injection pump, leaking injectors.
What about an exhaust resriction, clogged soot trap (converter).
When towing in the high temperatures, a few things add to the mix. Pulling hard and when the torque converter unlocks, the transmission creates a lot of heat, 280*F+ and even higher, which then enters the radiator to be cooled. That also helps heat the coolant. Plus you are going slower and less air is forced through the radiator, and now everything depends on the fan if the clutch is functioning properly. Is the A/C on as well? Thats more heat.
You said it runs hot. What was the coolant temps? Were they over 210*F? If so thats getting to the danger zone.
I would suggest a 12-V fan cooled transmission oil cooler, as this will save both the transmission and the engine, by keeping everything cooler.
Lets have some temps etc. so we can all help you. Wish you well. smile.gif

[rustypig]

I also believe pannhead to be on target here. Could also just be coincidence that it had been serviced recently. A $15 dollar vac gauge can save you a lot of money in the long run. Look for 20+ hg of vac coming directly off of the vac pump. Check the lines from vac pump to wastegate selenoid and then down to wastegate actuator for holes and rub-throughs (not uncommon).
Check codes if possible and see that it's not throwing any for your wastegate selenoid while your at it.

I'm pretty sure that the PCM will put the 6.5 in a catch 22 situation. Your pulling hard uphill....it creates heat...if the system (air, turbo, fuel, exhaust)is not in top shape it REALLY gets warm. The PCM notices hey, things are getting too hot here...cut fuel, cut fuel....you (frown on face) say hey...more speed please and ask for more fuel which creates more heat...and around the cycle goes.

[mtnedi]

WOW, thanks for the responses gents. To answer a few questions - it is stock with hd trailering package. The service consisted of the cooling system flush, transmission fluid flush, oil change, filter changes, etc.

Prior to the service, temp gauge normally registered 190-195. Now it is averaging 215-220. We have been hauling the camper and wife's horse trailer with her 2500lb horse all over the mountains for 3 years now and rarely did the temp gauge creep over the 220-225 mark - even on the hottest days. The 3 times that it overheated after the service the temp was approaching 260 and I shut it down immediately. In each instance, I replaced the coolant and water that overflowed and limped to destination.

The dealer service dept is telling me that I'm dealing with age of the engine and things are going to start going. This is my wife's vehicle and she really babys it - regular oil changes, filter changes, all at 3k or less. I can accept that yes it has 100k on it, but there were absolutely no indications of trouble on the horizon prior to this service.

I'm a computer geek and can tell you everything you want to know about computers, but when it comes to diesel engines, I am at the mercy of the dealer. Again, thanks for you input, it has been most valuable.

[tswartos]

im somewhat of a computer geek myself and i guess i know enuf about diesels to be dangerous :D

approach the situation the same u would troubleshooting anything else: what changed, when did it change, etc, etc.

based on what u've posted so far I'd say they've introduced something...check coolant color, tranny color, heck go to another dealer if u can. I took mine in for a pre-trip inspection as well and they found some things "wrong" until I mentioned that another area dealer had done the work they fixed at no charge (instead of the .5 it was gonna cost)...point is take it in let someone else diagnose issue b4 u say anything about who changed it all...might get lucky...good luck

[Black95TD]

I agree with pannhead. Loss of power and SMOKE = loss of boost. Check out my recent thread: Help, Intermittent CEL. I got some good feedback and the vacuum guage was invaluable in figuring out the trouble. My truck has 95K and after replacing the vacuum solenoid for $31, runs just as good as new. I would also recommend the Hayden fan clutch - check out some of the previous posts on cooling etc. I vote for the dealer knocking a vacuum line loose.

[rl22]

Those plastic vacuum lines get brittle with age and crack easily, just by moving them. I've had to repair mine twice with splices of rubber hose.

[david]

One thing i would do is change to 180 deg. stats.
Also if they flushed the rad. maybe they changed the stats also and they were not as good as the old ones.???
At any who put 180deg.in!!!!!!!!!!!!! :confused:

[HowieE]

Without a boost guage record to go on you should check to make sure you have vacuum source at the boost selinode input type. If this is OK and you have no other reason to think the turbo is not functioning I would look at the radiator. What type of flush did the dealer use? If they just poured in some stuff and drained it I would be suspicious that the radiator is now half full of dirt. Consider removing it and having a good radiator shop do a flow test on it. If the flow test is below normal have them clean and rod the radiator.

[mtnedi]

Thanks for the input folks. Had it back at the dealer and they could not find anything wrong. Am taking it to an independent Monday and providing him with your posts. Thanks again.

[mtnedi]

HELP! An update on the continuing saga. Took your posts to the dealer and an independent shop. Whether or not they used your posts for info I do not know, but both of them say they could not find anything wrong. They both said the boost is functioning to specs, the vacuum is funtioning to specs, and the clutch fan is functioning to specs. Yet I have the same problem - overheating, loss of power, and black smoke when hauling load up incline. The dealer tells me they are communicating with the GM techline but they say everybody is stumped.

You guys suggested gauges. I am going to invest in some, but need to know what readings I should be getting after I install them.

Thanks.

[britannic]

Although the symptoms are not completely consistent with a compression to coolant leak, I would recommend at least a compression test and coolant test for combustion gases if available.

I was a passenger in a tow truck recently that had a misfiring Ford Navistar diesel under heavy load and grades. The coolant temperature climbed through the roof (260F) and as the engine overheated, so did the intake air, which reduced the oxygen and increased the black smoke. We had to stop every 5 miles to cool down and refill the reservoir which was overflowing big time.

The head gasket was leaking combustion gases into the coolant that only became apparent under heavy load. As the coolant was heated by the high pressure gas, the symptoms worsened because the head was deforming due to heat expansion.

[HowieE]

Lets back up a step or 2. Why was the coolant resourve replaced? Have you lost coolant either before or after it was replaced? Let us know what the temperature is you are seeing on the hill pull and how fast it climbs to that temperature.
Yes a coolant pressure test and exhaust gas test are cheap and simple so how about that. The engine compression test would be nice but lets have the other information first and save a buck.

[mtnedi]

The reservoir was replaced after the first boil over. The dealer said it wasn't holding pressure. They also replaced both thermostats. After they replaced the reservoir, I hooked up the trailer and headed into the foothills. The temp gauge climbed very quickly towards the red 260 - sort of like watching the accelerator climb while accerlating. I stopped, turned around and headed back down the mountain and it cooled down.
I experience no problems hauling on flat land, only while climbing. Again, I have been hauling the camper or the horses all over the mountains with no problems for 3 yrs - this only started after they did their "routine" service. The third time I had it in to them was when they said they are stumped and are contacting the GM techline. This was 3 days ago.

[JCM5]

mtnedi,
Towing in hi elevations will cause a lack of power relative to elevation with any truck. I have experienced this myself. I have also noted that on hot dry days the truck runs worse. I also have noticed that not all fuel is the same. I can run hard on one tank and the next i can barely keep up.

I use Kennedys FTD additive, it does help. 3oz per tank.

As far as overheating, put in robershaw hi flow thermostats, 180 is preferdd. I would bet the dealer put in the OEM units, it does make a difference.

Radiator flush, i doubt it, unless you have a massive buid up of bugs. One thing to remember is to keep the air ducts up front clear. Those scoops at the boottom of the grill are not for lights.

[Don Boland]

I'm sure it is just me but the fact that he never had a problem until the dealer did their preventive maintenance work (wonder why they call it that? Seems like every time I let a dealer touch my rig I'm having something else fixed!), is when the troubles arose. That ain't lost on me, and it seems those dealer folks ought to be poneying up the fix! MTNEDI shouldn't have had to pay for the reservoir swap either under the circumstances. Where is the GM district dude on this one?

DB

94' CC Dually 4x4, 6.5td, Kennedy 3.5" exh, FSD cooler mounted on firewall outside of hydroboost - plug down! 189,000 miles

86' Suburban 4x4, 6.2, bad head-gaskets (they're next!), run's great but loses coolant! Wife hates it - I love it! 310,000miles

00' bug TDI, love the mileage and response and the OC's are easy. The rest is a pain to work on. JUST SOLD!

95 Suburban - 5.7 gasser; The wifes buggy!

[ucdavis]

You should be able to see daylight thru radiator/ AC condenser/ oil cooler stack. If not, you may have accumulation in the space between them that is killing cooling capacity, and it may have been driven there by dealer's guy blasting the radiator (don't know if that was done) less than completely.

Dealer may have (though should not have) put in one of the cheazy aftermarket thermostats w/ only 0.8 sq. in. of flow area each (vs. almost double that for good ones). I got one of these over the counter at NAPA last week, and compared it to TDP article photos; I'm pretty sure I'd be overheating ASAP if I installed it. See what part # they show as installed (not proof that's what went in but better than somebody's word) & look @ one out of dealer stock to see you've got right tstat unit.
180 tstats, tho maybe a good idea, won't do anything for overheat like this (absent bogus stats per above); once stat is open- its open & flowing to extent it can so 180 or 195 would be open at these temps.
Based on description of driving vs. heat, I'm inclined to believe gauges you've got, & that heat is real. Likely either loss of cooling capacity @ radiator due to service process, or constriction on coolant path getting to radiator (stats, passages in heads/block, hoses or pump). if you're losing coolant, might be hose leak, head gasket or pinhole in radiator.

[pannhead]

UC DAVIS might be onto something w/t-stats..the "flush" may have stirred up a big crud-ball and restricting flow...i would get your $ back on the resevoir,the resevoir doesnt hold the pressure..the pressure cap does....if you're 100 percent that you have boost give UC DAVIS post a good reading at...its probably going to end up being one of those easy things that can really mess things up...in realistic theory i would start "undoing" what the dealer did...good luck..i hope the DP solves this for you ;)

[ucdavis]

Another thought if shopping for service- I've got a great radiator shop in my neighborhood. They do hot rods, industrial radiators, & the usual consumer car stuff. They are the go to guys for race rigs. You've probably got one like them in the near vicinity. Most of these guys do whole cooling system work, not just servicing the radiator (stats, hoses, belts), but don't do much beyond cooling.

[charliepeterson]

Don't your later trucks have only one MAP sensor for telling the computer what the elevation is? My truck has two (OBD I). I don't think this will turn on the SES because the computer thinks everything is fine. If the truck pulls good below the hills then the computer might not correct for the elevation changes? I think any reader will tell you what the elevation above sea level is, you might have to subtract 15 from the number to correct for the pressure at sea level.
If the dealer steamed out the radiator they might have bent the finns over. If the knuckle head saw silver he might have thought he was doing a great job and removing ALL debris when he was actually bending the fins over?

[GARY PAGE]

I HAVE NOTICED MY TRUCK RUNNING HOTTER THAN I WOULD LIKE TO SEE WHILE RUNNING THE AC. THIS SUNDAY WHILE HAULING ABOUT 6500LB IN 92 DEGREE TEMP WITH AC ON SHE WENT TO 210 AT 70MPH ON A GENTERL GRADE, I WAS WATCHING IT REAL CLOSE. I BACKED OFF AND THE FAN THEN HIT HARD LIKE AN AIRPLANE AND PULLED DOWN TO BELOW 200 AND I TURNED OFF THE AIR. THIS CONDITION SEEMS TO HAPPEN WITH THE AC ON. THE AC APPEARS TO RAISE THE TEMP BY 15 DEG IN HOT WEATHER. I THINK MY FAN DOESNT HIT AS EARLY AS IT SHOULD. FRANKLY I WOUULD NEVER LIKE TO SEE MY ENGINES OVER 205 DEG. DOES THIS SOUND RIGHT

[rustypig]

I second on the t-stats. The only thing I would run is Robert Shaw brand Part #330-180 for your rig IIRC. They'll flow a ton more than a disc type t-stat.

One thing to check is the temp where your fan clutch is kicking in (if at all). Look at the front of it at the bi-metal spring. Is it covered with a 1/2 inch of grease and grime?

I noticed the EXACT same thing as Gary Page mentioned above. A/C on = 10 to 15 temp increase like right now. Since doing the dual thermostat cross over (w/RS 180 t-stats), new fan clutch and 21" composit DMAX fan conversion....things got WAY better.

I would REALLY recommend you get gauges. It's scary to think what EGT's you may be hitting if the water temp is pushing 260*! After having boost/egt gauges you'll never even consider driving a 6.5 by the coolant gauge!

[charliepeterson]

If you ever find grease or oil on the front of the fan clutch it's toast.

[SFD]

I had the same problem on my 98 Suburban. I just bought a 21 in fan and fan clutch from Bill Heath and towed my 7500lb trailer in 90 degrees and A/C on and temp guage went up to 205/210 and fan clutch kicked in and went right down to 190 deg until I hit a hill again and same results. Before installing my tems went uo to 220 to 230 and then kicked down and stayed around 200. Excellent product!

[SFD]

I had the same problem on my 98 Suburban. I just bought a 21 in fan and fan clutch from Bill Heath and towed my 7500lb trailer in 90 degrees and A/C on and temp guage went up to 205/210 and fan clutch kicked in and went right down to 190 deg until I hit a hill again and same results. Before installing my tems went uo to 220 to 230 and then kicked down and stayed around 200. Excellent product!

[patrick m.]

these are all good sugestions, so let me add one more.
If the dealer's service tech got the ratio of antifreeze/water way, way off, this will affect the heat transfer rate. water has a much higher rate of heat transfer than "antifreeze". if the cooling sys contains too much anti-, higher cooling sys temps will result.

my opinion is: it worked fine before they worked on it, and now it runs hot.......something went wrong while your truck was in their hands.
Who posted "redo what they did", ? that gets my vote.

[britannic]

Here's another option: check the water pump flow and belt tension. It's not unknown for a water pump impeller to start disintegrating.

Airlocks can also cause overheating, but the GM cooling system is pretty good at self bleeding.

[richard7]

I too would put 100 bucks ;) that the antifreeze concentration is way too high. This will kill the cooling system capacity by half, lower the boiling point and will not provide the corrosion protection as it needs water to work.

Did anybody check it? :rolleyes:

[mtnedi]

Thanks again for your guys input. Have another appointment on Wednesday and again I am going to give them your posts and have them check each one of the issues out.

[LanduytG]

If you now have black smoke and you did not before like others check the waste gate control. Another thig if you are lacking power and if its boost related that can also cause the temps to be high because youare not pushing the same amount of air through the engine. The air helps keep it cool as well. When I jacked up my boost egt's came down which will in turn cause it not to heat up as much. All these mods are great but if you did not have a problem before there is know need to change anything. First get a boost gauge so you can see for sure what kind of boost you are producing. Check the anti freez concentration although I bet its fine. T stats by all means I would change those to Robert Shaws but I would use the 195*. I will get flamed for saying that I am sure but I have tower my 5th wheel all over the USA and have desided the 195* make the truck perform better than 180*. I am not alone on this as I beleive JK found the same thing. Not only that if you are having and over heating problem colded stats won't matter any away. Mine is a 95 and I have never had any over heating problem except when the fan clutch got weak.

Greg