Coolant leak 1998 4X4 Tahoe

Hello all,
1998 Tahoe 4X4 5.7 Liter Automatic.
Coolant leak which appears to be at the back of the engine on Passenger side.( slow drip at bell housing and transmission pan has lots of dropplets
all over it.) 140,000 miles. Has not been abused or overheated.
This problem started last weekend. I started checking from the front to the rear of the engine. Water pump, hoses all inspected good no leaks. Replaced the fitting for the heater to the manifold, No help. I am slowly tearing down more extenal stuff on top of the engine to pinpoint leak.
Any problems with this model ? Is it possible the intake manifold is leaking at the back corner.? ( I sure hope not. )
Truck was purchased new and has not had any cooling system work done except the water pump and hoses @ 100,000 miles. Always has had Dexcool in it.
Look forward to all replies.
Thanks John
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I would be willing to bet anything that it's the intake gasket. An endemic problem on all of these 5.7's. Happened to my '94 K1500 Suburban at about 100,000. Since it was winter (Alberta, -25F) and I was pressed for time and heated garage space, the dealer did it. About $500 or so if memory serves me, but I had them do a chemical rad flush and coolant change at the same time, as well as a required oil/filter change for coolant contaminants. This was about 4 years back, and I was told the new style intake gasket was not prone to the problem.
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wrote:

The problem is kinda cronic on Vortec 350's because there is only 8 bolts holding intake on vs 12 with TBI and carb 350's. GM skipped the middle bolts on VorTec which leads to intake wanting to creep around a bit more from heating and cooling. GM redesign the intake gasket for it in late 2005. I had this gasket fail twice on my 2000 K3500 with a 5.7 in it. Once at about 30K mile under warranty and again at around 38K out of warranty. GM fixed it for free second time last year and "promised" it would not leak again. Using a lower pressure radiator cap helps extend seal life too. (I do now since second seal failure) ----------------- TheSnoMan.com
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The gaskets fail because the aluminum lower intake manifold expands at a different rate that the cast iron cylinder heads, the OEM gasket design is so poorly designed that it can not withstand the shearing that occurs between the manifold and the head. Better designed gaskets do not fail ruling out your 'missing bolts' theory. Also, were the failures due to 'missing bolts' it would stand to reason that the failure point would occur in the area of the lower manifold where the bolts were deleted, since this doesn't happen, further evidence that your theory is nothing more than armchair supposition.

Except that the leaks do not occur where "GM skipped the middle bolts." Further, the 4.3 Vortec engine also uses 8 bolts to mount the lower intake manifold which -should- result in a more secure and rigid attachment, yet the gaskets on the 4.3 fail at the same interval and same mileage as do the V-8 engines.

Came up a little broke did ya?

Hilarious! The great Snoman, knower and seer of all things can not keep his own truck from puking coolant without resorting to kluge fixes.
The "fix" is a more durable gasket (not OEM), not more bolts. More bolts would only result in the badly designed OEM gasket tearing in more places than they already do.
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On Sun, 04 Nov 2007 10:40:15 -0600, aarcuda69062

No armchairing at all like you do all the time. Sure it has a different expansion rate but because it is not clamped in center it is going to tend to expand more in center (bow out a bit) and dig in a bit on ends and usually they leak on ends after many cycles. If it was better clamped it would likely hold/seal better because intake would stay flatter.

For reasons stated above though it likely escapes you

Were do you get this. They told me that it should not have failed again and that a new style replacement was avaible. GM in Detriot authorized the free fix it and even gave me a nice rental car too. If you want to pay for something that you should not have to knock yourself out!

Typical ignorant troll comment. Been runing lower pressure cap on many cars for many year and never had one overheat or puke as you put it. (heck, they do not even get warm ever) Been up Pike Peak twice with one on my old Burb and been through 10% plus to with A/C and it has never exceeded 210 in 18 years and 180K plus miles. This vehicle still has original hoses and they look like new and it has never leaked. Plus if you were ever to get a leak it would be a LOT less explosive with a low pressure cap. One more thing that likely escapes your troll brain, the high pressure cap it there to help minimize gas bub barrier that forms on a hot part when water or a lower mixture ratio coolant contacts it which retards heat transfer (this is why some car can pop off after shut done and BTW, temp sensor reads coolant not actual block temp) I have been using 70/30 for years with increases heat transfer efficency This is why there is a myth that they run cooler with water because glycol transfer heat better from parts and has a a much higher heat content too (take more heat to heat same amount of glycol as water) and glycol weighs more too. The higher ratio raises boiling point so less pressure is needed. One more thing, if you ran pure Propylene Glycol (non toxic antifreeze) you would not even need a pressure cap because it freezes around 90 below and boils around 345F at sealevel pressure. (They likely do not teach physics in troll scholl so I may be wasting my breath with you.

Your lack of physics knowledge really shows. Extra bolts wouls help some and the 5.7 OEM gasket was completly redesigned in late 05 and the 4.3's a littel before that so while there was problem with past gasket, they may have it fixed now. (no doubt why they offer to fix mine for free because there has been problems with them. ----------------- TheSnoMan.com
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"No armchairing?" That's an absolute laugh coming from someone who had someone else replace the gaskets on his truck.

It's going to expand more in the center, eh? Neat trick.

As supported by the driveability problems that arise [not].

Too bad your theory isn't supported by the way the gaskets fail on the Buick 3800 engines. As you probably [don't] know, the Buick 3800 uses 12 bolts to fasten the lower intake manifold and the coolant passages are near the center of the cylinder head, yet the gaskets scrub and tear the same as the Chevy engines. So much for your "expands more in the center" and "digs in a bit on the ends" theory.

For reasons stated above, your theory is not only in error, it's 100% knee-jerk. Know why it's knee-jerk? Because all you've seen of any of this is the outside of the engine, all you've seen is some bolts that GM used to use aren't there anymore. You might become a little more enlightened if these engines were as transparent as you are.

Are you saying that GM called you and offered to replace the gaskets a second time just because they're nice guys?

You must have pitched a royal fit.

The truck was out of warranty, "should not have to" translates to pissing, moaning, whining.

Nice back pedal. I'll go with "I do now since second seal failure."

Another tangent.

"Explosive?" You put explosives in your cooling system?

The cavitation damage to your engine is probably worthy of the textbooks.

Gee, thanks for sharing that.

All bullshit, but I was wondering how long it was going to be before you hopped on your 'coolant' soapbox.

So, if pure Propylene Glycol is so good, why aren't you using it?

I never claimed to be a physicist, but I do know first hand what the engineers at the OEM gasket supplier to GM have to say about why these gaskets fail and it certainly doesn't jive with anything you're saying.

"Completely redesigned?" You DO love to show your ignorance, don't you. Redesigned by another vendor who sadly isn't supplying GM -or- their dealerships with warranty parts.

Yeah, it's fixed, they redesigned the engine with a dry manifold. Yours however will fail again and each time it does, coolant is migrating into the crankcase washing the main, rod and camshaft bearings.

You just keep an ear out for that phone call...
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snipped-for-privacy@sbcglobal.net says...

He will put HC's in his AC system so don't be suprised if this is true...
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On Mon, 05 Nov 2007 20:12:19 -0600, aarcuda69062

I was going to replace mine myself but if they are going to do it for free and warrant it I do not have ego issues about it.

Nothing neat about it (your lack of physics shows, a Troll short coming I guess) The is more mass in center and aluminum expands more with heat so center will "grow" more on intake side and stress will build up and it can only bow out to relieve stress which forces ends in a bit and that "worries" gasket on end.

And why? A few thousands of shift is likely not enough to beak seal in middle and there is no pressurized coolant in middle to "test" it but it will take a toll on gasket at ends over time. (again I know armchair Trolls have a lot of trouble with physics).

No my theory is sound. The fail a lot more and sooner on SB V6's and V8's. (especailly V8's) Another problem is coolant. Mazada recognized in 70's when they first cam out with rotary that 50/50 anything is not good on a mixed alloy engine because of the galvanic reaction setup by disimular metals can take a toll on gaskets between them too. GM's Dexi was a attempt to stay with 50/50 to save fleet coolant costs but is has not gone as planned. (Trolls never look past their nose or at biggers picture of causes and effects)

I guess I have to keep it simple for a simple minded Troll like you because you forget what you have read 5 seconds ago.

No, I contacted GM myself and they offered to fix it for free. Dealer I bought truck at suggested it because they are troublesome. GM in michigan made sure latest gasket was used and replaced everything related to it even Tstat and even asked for old gaskets back to verify reason for failure. I did not have to twist their arm and they even offer 1 year free maintainance too (which I never used)

Nope, see I am not a Troll like you and I have bought GM products for years (likley before you were born and surely before you even though of driving) and they knew it and that I was not a whiner like you

Maybe if you are a hot headed Troll like you. It was VERY pleasant. No real fuss at all. GM called me on phone to set it up after I sent them a query. See you are used to acting like a child to try to get your way but it is not the norm for many nor is it even needed a lot of time if you are a credible client unlike you.

Yes it failed agin BUT, it was minor and did not require instant repair with cap. It was loossing a few oz's a week or so at most and over a period of a few months I saw that it was down a little. Had it been a stock cap, it would have lost a lot more.

That is dismiss it when you cannot understand it. Typical Troll.

Another Troll answer, 15 or 16 PSI coolant can be a a lot more "explosive" (meaning force or violence of leakage) in a hot engine leak when is flashes to steam than with a lower pressure cap but you lack of physics understanding painfully show through as you try to CYA

Where did I say "cavitation" at Troll??? Again you have not studies heat transfer for hot surface to water nor surface tension or water vs glycol nor heat density of them. But as you usually do, if you do not understand it (which is a lot of things too) you attack it but in doing so you show how little you really know.

If it recorded block temp you would see it was coolant with higher glycol content than lower content.

Of course a Troll like you would call it BS because you have NO knopwledge of physics, surface tensions or liquid, energy density (amount of heat it can absorb) and so on. So sad!!!!

It is expensive and hard to find. It is used in Artic conditions like at the poles. If I ever find a good cheap source for it I will switch to it untill them I will run between 70/30 and 80/20 (the range I shoot for) with "toxic" anitfreeze. BTW, I do have several gallons of Propylene Glycol in my boiler for house (about 10 gallons of so) to provided freeze protection fo hot water heat system if heat fails in extreme cold some winter (it never has). Nice thing about using glycol is that even in lower constentations (warmer freeze points) water does not freze solid and expand the same way and it will not easily split pipes (or engines) but they may have not taught you that in troll school either.

If you do not understand physics you should not debate something that you do not understand (but if you only debated what you did fully understand you would have nothing to debate)

Sure GM out sourced it but they speced/requested design change.

I am not concerned because both leaks had no trace of coolent in crankcase. BTW, the "problem" with antifreeze in crankcase is that it does not wash the bearing but they is can combine with oil under heat and presuure and create a frictional cohesive that can damage and wear out bearing far quicker than plain water mixed oil can. They also make a specail flush to remove traces of antifreeze from crankcase and I have used a it a few times. (I bet that is not in your Troll manual either)

Why, I have not contacted them about anything else though I should off the way my 2000 eats brake lines were they cross frame near exhaust manifold, I have replaced myself all three of them as they rusted badly there and no where else. Engine oil coolant line are poor quality too and they tend to rust out as well. ----------------- TheSnoMan.com
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You don't have "ego issues?" Dude, that's all you've got. Why else would you keep coming here masquerading?

Here's a picture of the lower manifold;
http://partimages2.genpt.com/partimages/631258.jpg
Even a blind man can see that what you claim is bullshit. Also, please explain how bolts in the vertical plane can stop movement in the lateral plane. IOWs, how do fasteners oriented as I-I control movement <->

Well, is it a "few thousandths" or "bow out a bit" due to the "more mass in the center?"
Are you that stone stupid that you can't see your own contradictions?

So, on planet Snoman, things bow out in the middle due to more mass but they only move a few thousandths. You are claiming two things that can't occur mutually at the same spot on the engine. (not surprising)

More bullshit.

Now you're claiming that galvanic corrosion causes plastic intake manifold gaskets to fail. or, maybe you thought that would be a good place to insert some incoherent gibberish. <shrug>

GM implemented a coolant that cost twice as much as conventional green coolant to save fleets money? That's a good one.

The only person who has forgotten what they read (or posted) 5 seconds ago is you bozo.

IOWs, you called them and complained about a failure that was out of warranty.

Of course they did, you were out of warranty. They weren't going to do it until they knew they'd get paid. They wouldn't even call on your behalf you fool.

Seen it many times, replace everything and anything related to make sure the pain in the ass stays gone.

IOWs, they went in the warranty bin in case there was an audit. Standard operating procedure.

There ya go, contradicting yourself again. Why wouldn't you take their free maintenance since it was free? That was the determining factor when it came to replacing the gaskets wasn't it?

Unlike you, I know better than to buy a truck riddled with known catastrophic failures.

Okay, I'll take that bet; what ear did you buy your first GM vehicle? (it's put up or shut up time)

No doubt it was pleasant, you dodged having to work on an engine that obviously scares the bejesus out of you.

After you checked to see what freebies you could get out of warranty.

I don't -need- to get my way, I am perfectly capable of repairing my own vehicles.

Another contradiction there Snofool. "I do now since second failure" doesn't jive with your claims in the above paragraph. Me thinks you're nothing but a common garden variety story teller.

I'm not dismissing anything. What does your shitbox 89 Suburban have to do with leaking intake manifold gaskets on a 98 Tahoe?
Has it ever occurred to you that these side tracks of yours make you look like an even bigger buffoon than that which is being documented and cataloged by others?

Here's news for ya; so can filling your AC system with hydrocarbon refrigerants. Another contradiction.

Why would it flash to steam, you've claimed earlier that your coolant doesn't get hot enough for that to happen. YA (yet another) contradiction.

You didn't, I did. Pity the poor bastard that gets stuck with that piece of crap.

So, you think 16 pound radiator caps are just a great big conspiracy to take you out, eh?

WTF is THAT gibberish?

I sure as hell hope I have no knopwledge of physics. I hear that those knopwledges are mighty noisey and hard to tame.

I should have pointed out here that the correct numbers for propylene glycol are -76* (freezing point) and 370* (boiling point)

Looks like they don't teach physics at dumb fuck school either.

So expensive and hard to find that it's a common food additive.

Yeah dumbass, because it's less likely to poison the wildlife if there is a spill, not because it's a better coolant.

Again, cheap is good yet you turned down free maintenance.

You have me confused with someone who gives a shit.

Toothpaste has propylene glycol in it, you should fill your boiler with toothpaste.

Hey dipstick, I didn't say I didn't understand physics, I said I never claimed to -be- a physicist, but don't let that stop you from further projections.

No, you need to show, describe, prove this complete redesign by GM.
Someone else did a complete redesign you numbskull.
Now show evidence of GMs complete redesign. (maybe it's over there>> next to the recall on Triton spark plugs you claimed in another *group)

They would have no way of knowing that short of sending the oil out to be analyzed and GM doesn't pay for oil analysis unless it's going to court.

Blather on...

Who is "they" and what is the name of this product?

All known common problems on GM trucks for years and yet you were stupid enough to buy one anyway. Yup, you da expurt on physics awlright.
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I'll second it, intake manifold gasket leak. Did my '99 Yukon at 90k miles. Not too bad a job if your a motorhead. Don't forget to get a new "quick release" heater hose connector before you start. It's the connector at the front pass. side of the manifold for the heater hose. It will snap right off when you go to remove the hose. It's cheap an was in stock at my local dealer. It's made of pot metal and will chip out of the manifold easily when you have off.
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