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1997 GMC g1500 5.7L, Coolant Disappearing!


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DragginTheLine...
Novice

Apr 3, 2022, 5:32 AM

Post #1 of 7 (1484 views)
1997 GMC g1500 5.7L, Coolant Disappearing! Sign In

Hey guys, been struggling with this issue for a while and I'm having a hard time getting to the bottom of it. My 1997 GMC Van goes through coolant like crazy, definitely have a leak somewhere but ive already checked the reservoir & hoses for cracks, replaced the water pump, engine oil looks good, no white exhaust smoke (beyond the normal bit of smoke I get on startup), Van runs perfectly as far as I can tell. I purchased a new radiator cap because mine is worn, but haven't put it on yet, honestly though I have a hard time believing im losing coolant at this rate over a radiator cap.

Looking for ideas on what to try next. Am I looking at a cracked radiator maybe? Should I just go ahead and replace all the hoses as a matter of course? What do you guys think?

Appreciate any ideas !


(This post was edited by DragginTheLine... on Apr 3, 2022, 5:37 AM)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Apr 3, 2022, 5:44 AM

Post #2 of 7 (1477 views)
Re: 1997 GMC g1500 5.7L, Coolant Disappearing! Sign In

Keep it full for right now!
Is this a Vortec? Should say so on it or I think "R" is 8th digit of VIN#. Intake manifold is somewhat common even twice by now.
Might see it down the rear over trans is coolant not oil. Find it note it will wash off with water an oil will not.
Check all coolers up front (lots of them) that use or hold engine coolant too it's hard to see the actual radiator most use so many things to cool, PS fluid, oil sometimes, trans thru radiator or separately in the way.
Make it leak with a pressure tester just do not exceed 15lbs, engine off should make it an active leak.
Again the intake is common and involved if a Vortec means more work or money hope things don't break if that to fix it.
There are improved gaskets ask for the set,


Tom



DragginTheLine...
Novice

Apr 3, 2022, 5:55 AM

Post #3 of 7 (1473 views)
Re: 1997 GMC g1500 5.7L, Coolant Disappearing! Sign In

Yes, it is a vortec. Appreciate your input!

Can you elaborate further on this common issue with the intake if a Vortec is involved?


(This post was edited by DragginTheLine... on Apr 3, 2022, 5:59 AM)


Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 3, 2022, 7:05 AM

Post #4 of 7 (1462 views)
Re: 1997 GMC g1500 5.7L, Coolant Disappearing! Sign In

Yes - I own one now - same model year bought @ 34k ~ 7 years old odd for me but from a new car dealer. Happened right away the did it within just a 30 day mandatory warranty I let them.

It's seeping a bit again now over 25 years old different game in a pick-up HD everything layout different than van but not the engine.

Yours if so I'm not sure nor are you yet but yours is fast isn't going to take tricks. No longer sold is a clogless sealer suggests use a whole bottle (never do that) use an ounce it quit again! Slow would only find it low once a year. I also use lb closed system pressure caps you can't on a van mine uses a thermostatic clutch that works well never changes now only 72K.

That's why OMG gettin' old sport can't do everything myself alone a seriuously talented super tech said it needed another. I then added a second ounce and it's gone again.

Job thru him was to be about $900 bucks (not the point) he has more help for stupid things that get heavy sometimes I don't.

It's at least the 5.7 that had this issue IDK on also other Vortecs? I don't see everything ever made never mind this old. There may have been a 5.0 same engine really + same year family owned never did it??

If so it can drip anywhere it seals but down the back was mine no noticeable loss of coolant and held pressure, does now too.

Your call it's an involved job but if keeping this and nice enough either take it on or find the right folks. The distributor in these is also not for adjustment know that! Looks like but no.

So it take high end tools to set it if touched meaning removed.

If engine is healthy and this van still good otherwise go for it new is out of control costly so room to spend if in fact that's it.

I've loved but ask now if Felpro brand gaskets are still best. They have been better than OE on tons of things for me.

Being a van this super needs a good cooling system the pick-up shape gets more air.

You won't like it but think about a new clutch too those add another huge bunch of bucks.

This should roar when hot like stopped when hot out, fully warmed up stop at a light for a while take off and OMG sounds like a propeller of small plane taking off feel it drag too.

Any fluctuation of temp on gauge means a problem on these - vans too. It goes to right there spot (note it) and doesn't go up or down all seasons has been -4F here and 104F within a year plus all the years I've owned this stayed the same at any temp A/C cranked and all with window open so cold!

This is one of the last CAST IRON small block Chevys if you will the most bulletproof thing made you'll never know another again.

This was powerful again of decade+ of lame crap out there.

You didn't ask but one good way to know engine is good is watch oil pressure gauge from cold start up. It should shoot right up 1 second no delay.

Other cheap trick is smoke (idling) will go down where the diptick tube is if pulled up or out! Mean blow-by doesn't exceed just a PCV is great news for this generation of cast iron engines.

Be sure! I could be wrong and this a waste of good time and $$ if something else a pressure test should show it, it's fast as you said,

Tom



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 3, 2022, 10:45 AM

Post #5 of 7 (1453 views)
Re: 1997 GMC g1500 5.7L, Coolant Disappearing! Sign In

You approach this like any other coolant leak. You pressure test the cooling system and you keep it under pressure until the leak shows up.



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DragginTheLine...
Novice

Apr 3, 2022, 12:20 PM

Post #6 of 7 (1445 views)
Re: 1997 GMC g1500 5.7L, Coolant Disappearing! Sign In

Really appreciate all the info. I'll go ahead and do a pressure test and see if I can't find the leak somewhere obvious.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Apr 3, 2022, 1:32 PM

Post #7 of 7 (1434 views)
Re: 1997 GMC g1500 5.7L, Coolant Disappearing! Sign In

Mirrors, lighting. Leak's source is usually highest and most forward of evidence. Since fast wipe area to be certain watch it return, Tom






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