Hey, just a heads up for you guys running Vortec 350's, It could apply to other Vortec motors too. My wifes DD is a '99 Tahoe with the Vortec 350. Bone stock grocery getter with 95K on it.

The heater return line drops into the intake manifold right behind the alternator using a snap fitting. For the past few weeks I smelled coolant but couldn't find a leak and no loss of coolant. Well long story short, the whole snap fitting fatigued at the manifold and just fell off. Spewed everywhere.

After close inspection it turns out the fitting that screws into the manifold is actually plastic with a very thin skin of steel. The plastic was literally falling apart and the metal skin couldn't hold the vibration loads and just fatigued apart.

I talked it over with my local dealer and they see several of these failures per week. Their standard practice is to replace the fitting ANY time they work on the cooling system just to avoid this very type of failure.

The replacement part is only $9.50 at Pepboys and is made of solid steel. It only takes a few minutes to replace. The counter guy at Pep Boys keeps 10 on hand because of the demand.

On a side note, I replaced the fitting on my brothers 99 Tahoe with 84K and the fitting came right out. The plastic was just falling apart but the metal was still solid.

Now how to teach the wife that it's not OK to drive with the needle pegged at 280? :(

Yep, had that happen to me with 40,000 miles on the truck. Its a 98 silverado, and quite possibly the biggest POS I have ever owned. :skull:

Yep, They go out every couple of years.. It is on my 94 work truck.. I think I have replaced it 6 times... Lots of fun..

TBI engines have a similar problem with a pot-metal fitting at the back o f the intake. Tried to replace it in my truck and it broke off in the intake!! Took two days to get it fixed, and it still leaks some. Now every time I have one of these engines out I replace that fitting with a standard nipple, to avoid similar problems.

What were they thinking!?!?!?!

I've been searching through the archives because I've had trouble with my '89 TBI coolant fitting. I'd like to replace it with a brass fitting, but I've heard rumors that it has to have the correct restriction in it or the thermostat won't open correctly. Anybody ever had problems or success with changing it?

napa auto parts has a replacement that is made of actual metal. kudos on the searching.

I've gone to the straight nipples used on pre '88 trucks and replace the heater return line or just lop off the fitting at the end depending on the number of miles on it. I'm running the straight fitting on two different trucks, one 454 and one 350 without problems.

The truck I originally posted this about is running the Pepboys steel replacement with no apparent problems.

One final note. I have a '92 2 door Tahoe with 203K miles and it still has the original pot metal fitting on the 350. It still looks new.

Hey, just a heads up for you guys running Vortec 350's, It could apply to other Vortec motors too. My wifes DD is a '99 Tahoe with the Vortec 350. Bone stock grocery getter with 95K on it.

The heater return line drops into the intake manifold right behind the alternator using a snap fitting. For the past few weeks I smelled coolant but couldn't find a leak and no loss of coolant. Well long story short, the whole snap fitting fatigued at the manifold and just fell off. Spewed everywhere.

After close inspection it turns out the fitting that screws into the manifold is actually plastic with a very thin skin of steel. The plastic was literally falling apart and the metal skin couldn't hold the vibration loads and just fatigued apart.

I talked it over with my local dealer and they see several of these failures per week. Their standard practice is to replace the fitting ANY time they work on the cooling system just to avoid this very type of failure.

The replacement part is only $9.50 at Pepboys and is made of solid steel. It only takes a few minutes to replace. The counter guy at Pep Boys keeps 10 on hand because of the demand.

On a side note, I replaced the fitting on my brothers 99 Tahoe with 84K and the fitting came right out. The plastic was just falling apart but the metal was still solid.

Now how to teach the wife that it's not OK to drive with the needle pegged at 280? :(
Is this fitting on the Vortec454's? My girlfriend has a 99 Suburban with a Vortec454 and it loses a little coolant and smells of antifreeze a little, but I have not found where it is going. I was afraid it was a head gasket. What is the partnumber of the fitting you got from Pepboys so I can go look at it and compare to the one in the burb...

Mark

The fitting is the same on the 454 and the 350's. I do not know the part number and I did not keep the receipt. One word of caution on the 454's: The intake manifold on the Vortec motors is aluminum and has a VERY thin cross section. It is VERY easy to overtighten the fitting and crack the intake manifold. Changing the lower intake is not a fun job. I refuse to comment on why I know this. :(

Take a look at the intake to the right of the alternator right in front. There is a coolant line that comes into the intake manifold with a snap fitting. If there is coolant or a white crusty buildup around the fitting you should replace it.

There are only two different fittings. A bigger one for the earlier models and a smaller one for the later ones. Autozone carries them also, and they are really common to go out. My dad had to replace one in my mom's old 92 Blazer, which was about 5 yrs old, later her 99 GMC, it was about 2 yrs. old, and recently the one on his 95 work truck. I would advise that you change it out before it starts leaking, they can be a real bitch to get out.

Why mess around and screw a chineese steel part back into an aluminum
intake just to do it again later? Poor GM design,no doubt.Just go old school and cut end of heater hose and use standard heater hose fitting with stainless hose clamp.If you want to retain factory restriction that most original and replacement fittings have, put together brass nipples,reducers and
heater fitting to intake manifold.

Hey, just a heads up for you guys running Vortec 350's, It could apply to other Vortec motors too. My wifes DD is a '99 Tahoe with the Vortec 350. Bone stock grocery getter with 95K on it.

The heater return line drops into the intake manifold right behind the alternator using a snap fitting. For the past few weeks I smelled coolant but couldn't find a leak and no loss of coolant. Well long story short, the whole snap fitting fatigued at the manifold and just fell off. Spewed everywhere.

After close inspection it turns out the fitting that screws into the manifold is actually plastic with a very thin skin of steel. The plastic was literally falling apart and the metal skin couldn't hold the vibration loads and just fatigued apart.

I talked it over with my local dealer and they see several of these failures per week. Their standard practice is to replace the fitting ANY time they work on the cooling system just to avoid this very type of failure.

The replacement part is only $9.50 at Pepboys and is made of solid steel. It only takes a few minutes to replace. The counter guy at Pep Boys keeps 10 on hand because of the demand.

On a side note, I replaced the fitting on my brothers 99 Tahoe with 84K and the fitting came right out. The plastic was just falling apart but the metal was still solid.

Now how to teach the wife that it's not OK to drive with the needle pegged at 280? :(

Pegged at 280? Ouch. You sound like youre getting out pretty cheap considering what could have happened. I guess GM's don't have a shut down feature if the engine gets too hot.

This problem is common enough that there is a special too available to remove the broken potmetal fittings from the intake without having to remove it. It looks like a two stepped splined easy out. I don't recommend the spiral type, cracked an intake that way once. Ouch :(

We see quite a few of these in the shop. Horrible idea from GM, the stock fitting breaks off every time. Have to grind the fitting out to where you can see the threads then retap it. Replacements at all the parts dealers are solid steel.