lb7 engine not getting to operating temp

[01DURAMAX]

finally received my injectors from gm after waiting 3 weeks for them so i was able to do the injector swap. everything went well, overall not too bad a job. trucks not smokin anymore and running excellent. i have plenty of heat and the coolant level is staying right where it should after bleeding the system several times. it seems as though the coolant system isn't building pressure but as i said the level is staying where it should. oil level is also good. anyone seen this before? could there still be an air pocket somewhere?...i did pull the drain plugs on the block as well in order to change out all of the coolant. again this is an 01 lb7. any help appreciated.

thanx
-Dave

[DmaxMaverick]

Are the thermostats still original? If so, you should have replaced them when you did your complete coolant service. Now, while you are still messing with it, would be a good time. The originals are old by now, and could be sticking. Especially after a complete coolant change.

If you have air in the system, it will normally vary the coolant tank level, and blow out a lot of coolant. The temp gage will also fluctuate to extremes. If you did the bleed procedure according to the service manual, it should be minimal. An air bubble in the system is more likely to cause an overheat, rather than an underheat.

[01DURAMAX]

the thermostats are only about 9k miles old. i thought the same about runnin hot rather than cold but i can't think of anything else it could be. dependind on who you talk to the bleeding procedures are different. in all cases it seems that there have been many probs with purging all of the air out in these motors.

[DmaxMaverick]

What bleed procedure did you use?

[01DURAMAX]

i opened the bleeder and filled the coolant until the i got no bubbles out of the bleeder and the level in the bottle was correct. i started the engine and with the cap loosely on 1 thread and when the temp read over 175f i revved the engine from idle to 3k rpm in 30 second intervals but it never warmed up over 180f. i opened the bleeder to see if any air would come out but i just got strait fluid. at this point i decided to drive the truck in order to see if i could work the air pocket out if there is one. i took the truck home with me from my shop which is about 40 miles and then back again this morning. still same thing coolant level hasn't changed at all and engine won't warm over 180f. it is cold here approx 28f but it should warm up in that time. its a mystery to me. if anybody has any ideas.

[Mark Rinker]

Okay dumb question...is it possible that you aren't getting a good read of your engine temp - i.e. loose/broken sender wire?

Just a thought...

[01DURAMAX]

i suspected that as well not a dumb question. but i have the genesys scan tool and the highest reading that i am getting from the tool is 165.

[DmaxMaverick]

That's the correct procedure. There's only one effective way to bleed it, and you nailed it. I'd like to hear of the others. I think you can rule out air contamination at this point, due to your procedure and visible results.

I think if you are seeing 175°, it's close enough to call it good. The senders and gages are not that accurate, and a dose of fresh coolant may have loosened things up. I'd run it as-is, and watch for changes in trends, rather than the actual number.

[More Power]

180 (when looking the somewhat inaccurate dash gauge) is not entirely out of the range of normal when driving in cool weather and the engine isn't loaded all that much.

If you have the factory winter front, I'd install it for a test, or you could test the truck in some other way that loads the engine more (like towing at freeway speeds).

Jim

[kaylabryn]

Have you driven it or are you just letting it idle/reving in one place. A diesel takes forever when not put under aload to warm up. Just a thought.

Mike

[01DURAMAX]

I've put about 100 miles on it and still same thing. the truck has 153k on it and ive owned it since new. it always runs between 200 and 205.
the thermostats and head gaskets were both done 10k ago so all of the coolant was fairly recent. it just seems like a mystery to me

[moss6]

I'm not sure about your year model but the LBZ's will code if the temp is not high enough after a certain amount of run time. I know this to be true as my truck has coded (I think #0128 which goes something like 'temperature not up to thermostat level') as being too cool before; but with my modifications this is to be expected. If you have not had a code and your truck has that ECM coding then you are normal.
Randy

[lb7lbz]

i have an 01 that dosnt run over 175 degrees pulling my 20' enclosed at those temps dosnt seem out of the ordinary and gauge could be a little off.