Can't Find Antifreeze Leak

[Vetteman61]

Hello all,

My 99 Suburban (5.7, 4x2) has an antifreeze leak I can't seem to find. It comes down off of the dust cover. I can trace it up the passenger side rear of the engine. I think it may be coming from over the top of the valve cover, between the valve cover and intake, but I'm not for sure. It may be coming from below that area. The #8 spark plug appears to be wet also, however the truck sits on a hill facing down, so it may be running.

Is there a common issue on the passenger side rear on these engines that could help me locate this issue? I forgot to add that the overflow jug us loosing coolant while sitting but the radiator doesn't seem affected.

Thanks,
Brandon

 

[SAATR]

Intake manifold gaskets leaking externally, at either the front or rear passenger side of the engine. Very common issue.

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[Vetteman61]

Thanks for the tip. I was afraid of that possibility. From what I've read, the MS98000T is the preferred gasket set to go with. Are there any other typical problems that I should address since I'll already have the intake off?

 

[skylark]

Did the mpfi injector upgrade and replace the heater hose quick connect.

 

[Bob L]

I would look at the heater hose quick connect as mentioned carefully before pulling the intake. That is where mine was leaking.

 

[Vetteman61]

Thanks for the replies. I forgot to mention that I had this same leak two weeks ago, replaced the quick disconnect with a standard fitting and then found another puddle under the Suburban this morning. Apparently it's the intake this time.

I think I'm going to flush the coolant system out and use a regular green antifreeze, that way I can use the same stuff I use in all my other vehicles and I won't have to buy "suburban only" antifreeze.

I'm watching that 38 minute youtube video of the guy doing the intake swap now and I've read two other detailed posts on how to do this project in preparation for hoping to get it done, or at least mostly done, tomorrow.

 

[SAATR]

MS98000T is the preferred set, as you said. Mark the distributor and take plenty of pics during disassembly, should make things fairly straightforward. If you don't intend to replace the spider, it isn't necessary to remove the upper plenum to pull the intake. Cam save some headache and hassle later on.

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[sabbath93]

just did this job 2 weeks ago was super simple got the felpro kit came with More than I needed make sure you use some penetrating oil on the egr when you take it out I twisted mine off and it's a 300$ little tube so unless you want to spend time building a new one or deleting it out be careful with that

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[largewon62]

A little tip that I found when replacing my intake gaskets was to cut 4 pieces of all thread about 1 1/2 - 2" long to screw into the 4 corner intake bolt holes to help guide the intake straight down without messing up the silicone or end gaskets when dropping the intake back on. I cut slots in the end so I can use a straight screw driver to remove them when I am done.

 

[Vetteman61]

I'm not sure if super simple is an adjective I'd use, but then again this was my first time and taking pictures and figuring everything out was very time consuming for me. I'm used to older cars without so many foreign and "scary" electronics. And metric bolts??? What are we, terrorists???

I bolted the intake on today and got 4 bolts and cut the heads off and did just that. I do that with heads on straight 6s and things as well, has always worked good for me. I was surprised to find that the bolts holding the lower intake were standard and not metric. I suppose it makes sense if I consider that these head castings were probably old castings that had used standard, but it was still annoying. Two trips to the hardware store.