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Hello everyone,

This may be old hat for some but I have been searching this site for an answer and have had no luck.

I have a 98 gmc 3500 with the 6.5 in it. This has always been a very warm truck. However during a cold spell(very cold) my rad developed a leak over night. Not big just a little. I spoke with a mechanic and he said that is not uncommon for the flexible seal in the rad to shrink enough for it to leak. Sure enough as it warmed the small leak was gone.

Then on a trip to the city I noticed it wasn't very warm inside when I left but didn't think much of it. While stopped at a light i noticed it got cold almost immediately. Then when I accelerated on the green there was a cloud of white smoke behind me.

Talking to my mechanic again he figured I must have low coolant level(I didn't) or air lock. He said these engines do crazy things if they are not warm. I opened the radiator cap and ran the motor for about an hour constantly checking for the coolant level to dip to purge the air. It didn't dip and the temp didn't get any better either.

A couple years ago I changed the heater core and never had an issue with air lock at all. I did however come across a message here explaining how to purge the air with the release screw over the thermostat housing. Did that ...no luck. In fact when I stop the truck it gurgles and pops away. I turn the relief screw and there's a little more air. Also I can hear very faintly a high pitched noise sounding suspiciously like air movement being sucked in somewhere. Does this procedure have to be done numerous times or is air getting inside somehow?

As soon as I increase the rpms', heat is fine. As soon as I idle....5 seconds its cold. Also after idling for over 1.5 hrs the lower rad hose is cold, the upper hot. the return line to the radiator cap reservoir is cold to luke warm.

It seems there is definitely air in the system. I did notice that there is a quick connect at the thermostat housing for the line to the heater core. Is it possible for air to get sucked in there? I know many are thinking cracked head right now. There is no water in the oil, the white smoke I experienced is not the lingering sweet smelling smoke of a cracked head, and there is no discoloration at all in the reservoir and it smells fine to my nose.

I was also wondering if the clutch on the rad fan has failed and it runs all the time.

If anyone can help me out here I would be eternally greatfull

Jason
 

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Flared bumper nostrils
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Welcome, fellow Albertan
With the engine cold, the top rad hose should be soft. If you start it, and it instantly stiffens up. Head gaskets
 

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Good advice from injectorsaurus.I'd look into radiator replacement as well.A small leak now could be costly later especially if coolant spews everywhere.It does take some time to expel the air through the thermostat housing but after a few attempts of bleeding the system with the engine at operating temperature it should be okay.How old are the thermostats?I'd look into changing them with some acdelco replacements and give it another go.
 
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Flared bumper nostrils
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Are there any noticeable bubbles in the coolant tank?
What does your temp gauge show idling, driving or working?
When was the last time you added coolant?
Does it appear to lose coolant at all?

Take some time to fill out your signature
http://www.dieselplace.com/forum/profile.php?do=editsignature

My guess right now is still head gasket
 
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When cold, the leaky coolant is not evaporating right away.

Check the common area of leak first like the Coolant crossover quick connect on top of the engine. That quick connect are made of soft metal and it will break over time.

Be careful when changing it.
Use a SOCKET instead of open end wrench.
You need a large socket that is why people keep breaking it using open end wrench.
 

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Discussion Starter #6
you guys are awesome

Wow, what great responses,

Ok yes when engine is cold upper rad hose stiffens up in abut 10 seconds. However there is no coolant smell in the exhaust, no coolant in the oil and no coolant loss.

There are no noticeable bubbles in the reservoir, but there is vapor or steam when it is running without the cap.....but no heat in the fluid. I will check the crossover thing, however I don't see leaks anywhere other than the very tiny high pitched wheeze or suction noise after the motor is turned off.:think:

I have new thermostats but the ones in place seem to be working.The rad is only 2 years old, same with the heater core.Only had the one leak at -40c overnight and it was where the reservoir(cold side) meets the cooling fins.

I seem to be leaning towards the heads. What are the chances that it is just the gasket and the head will be ok? Why are there no typical signs for the head gasket? white sweet lingering steam in exhaust or water in oil.

Your guys' imput is greatly appreciated, much thanks

Jason
 

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Wow, what great responses,

Ok yes when engine is cold upper rad hose stiffens up in abut 10 seconds. However there is no coolant smell in the exhaust, no coolant in the oil and no coolant loss.

There are no noticeable bubbles in the reservoir, but there is vapor or steam when it is running without the cap.....but no heat in the fluid. I will check the crossover thing, however I don't see leaks anywhere other than the very tiny high pitched wheeze or suction noise after the motor is turned off.:think:

I have new thermostats but the ones in place seem to be working.The rad is only 2 years old, same with the heater core.Only had the one leak at -40c overnight and it was where the reservoir(cold side) meets the cooling fins.

I seem to be leaning towards the heads. What are the chances that it is just the gasket and the head will be ok? Why are there no typical signs for the head gasket? white sweet lingering steam in exhaust or water in oil.

Your guys' imput is greatly appreciated, much thanks

Jason
You need to forget about coolant in oil & white smoke. I'm nearly positive your going to need gaskets. It's possible the only symptom is excessive pressure in the coolant side.

I said in post #2, head gaskets
I said in past #4, head gaskets
And I've said in this post, head gaskets
So, Id day, yes, there's a good chance that it's the just the gaskets and the heads are fine :HiHi:

I love working on 6.5's, bring your truck to red deer & I'll diagnose and fix it for you
 

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I had a old Fordson diesel tractor that lost a head gasket - no coolant in oil or oil in coolant - but it started pushing fluid out the rad overflow tube because air was being pushed into the cooling system.

With your upper rad hose getting stiff and air getting in the system..it sure sounds like head gaskets.

Which isn't a death sentence for the 6.5 by any means! Just address it as quickly as you can!
 

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Discussion Starter #9
Sounds Awesome!

Just gets better and better round here. My email is [email protected]
If you send me your details I can call and set something up. I'm with you on the head gaskets just hanging on to a small flicker of an easier solution.

Jason:bow:
 

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Discussion Starter #10
Thanks

Thanks Rambos, I am hoping to have it looked at this week, actually by injectosaurus. Everyone is so helpful :clap::thankyou2:notworthy:


I had a old Fordson diesel tractor that lost a head gasket - no coolant in oil or oil in coolant - but it started pushing fluid out the rad overflow tube because air was being pushed into the cooling system.

With your upper rad hose getting stiff and air getting in the system..it sure sounds like head gaskets.

Which isn't a death sentence for the 6.5 by any means! Just address it as quickly as you can!
 

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Flared bumper nostrils
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Thanks Rambos, I am hoping to have it looked at this week, actually by injectosaurus. Everyone is so helpful :clap::thankyou2:notworthy:
Hey, haven't forgotten about you, just got tied up at work. Getting some parts ready for Crazyxxxinsane and getting some interior parts washed for my truck, and still need to do my crank seal and find a mystery coolant leak.
 

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Hey, haven't forgotten about you, just got tied up at work. Getting some parts ready for Crazyxxxinsane and getting some interior parts washed for my truck, and still need to do my crank seal and find a mystery coolant leak.

Injectorsaurus - Hello - Dan (Rambos Ride) here!

Just wanted to make sure it was Jason you were trying to get ahold of.

I'm interested to know what you all find out though!

Dan
 

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Injectorsaurus - Hello - Dan (Rambos Ride) here!

Just wanted to make sure it was Jason you were trying to get ahold of.

I'm interested to know what you all find out though!

Dan
Thanks, we're good. I'll call him tomorrow
 

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Not to recommend neglect, but...

My old daily driver had a headgasket starting to leak (stiff hose but no smoke/smell) and I run it hard for another 10k miles before I retired it. (xfer case/tranny/mouse infestation. Motor still runs) Just had to add coolant daily (and about every hundred miles when towing over 15k lbs)

Just saying, if she's your daily driver she'll probably hold together for a little while...
 

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Discussion Starter #15
Daily Driver

Thanks Broken Smoke. I do need the truck alread, will keep that in mind. Hopefully saurus'll help me git r done but if he hasn't the time I may have to start with the truck as is. Appreciate the info

Jason
 

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Discussion Starter #16
Just an update for those following..

Well Injectorsaurus came all the way out to my place for a look see. Definitely getting air into the system. Most likely a head or heads. We are hoping to just replace the gaskets and do the injectors as the heads will be out and it makes the most sense. Hopefully we find what we expect and nothing more.

For those wondering, the guy really knows his 6.5's and I am excited to have found him....gonna be my new BF!:hehe: He just maybe doesn't know it yet.

Will keep you all informed. Once again I thank everyone for their input and don't stop!!

Jason
 

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Discussion Starter #17
OK!

Drove the truck the 60 miles to injectosaurus. He as officially diagnosed that air is getting into the system from the passenger side head. We are hoping just the gasket but will know for sure this weekend!

fingers crossed
 

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BEST OF LUCK!:thumb:
 

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Discussion Starter #19
Quick note:
Injectosaurus has the truck.
There was a head gasket failure at the rear coolant passage on the passenger side head. Unfortunately that's not where it ended. Head was also cracked, turbo shot, other head cracked and in worse shape, injectors shot. Injectosaurus is knee deep in her now. He is going to give a rundown on it all as well as a time lapse video.

So glad I found this guy!!
 

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Quick note:
Injectosaurus has the truck.
There was a head gasket failure at the rear coolant passage on the passenger side head. Unfortunately that's not where it ended. Head was also cracked, turbo shot, other head cracked and in worse shape, injectors shot. Injectosaurus is knee deep in her now. He is going to give a rundown on it all as well as a time lapse video.

So glad I found this guy!!
Sadly, rarely is it just the head gasket!

Good you could find someone trustworthy to help get her running again.
 
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