Intake or Head Gasket Coolant leak???

[Gone Blue]

My 98 Astro with 100,000 miles has developed a coolant leak that is either the intake or head gasket. Does anyone have any good tricks to tell which one it is? It does not smoke and the dip stick and oil is clean. I had the dog house off today so I could have a better look at it. Coolant seems to puddle were the intake meets up with the head on the passenger side and drips off both the front and rear ends of the head. I am thinking it is the intake but not sure. What do you guys think? Thanks, G.B.

[swharris]

I have a '97, and I'd bet a saw buck that it will almost certainly be the lower intake manifold gasket. F'ing GM made the gaskets out of plastic I just finished this job, and while it's not pretty and could be a bit intimidating for a shade tree'r, it's well within the DIY realm.

Have you ever replaced the spider injector unit? If not, with a van of your age, I'd take the opportunity to replace it. You will have to take it out for the gasket replace anyway. You'll get better milage and performance from the new updated injectors and avoid another upper intake removal. Get it from GMpartsdirect.com they've got about the best price on it the last time I checked.

email me if you have any questions. swharris@mac.com

[01safari]

Without seeing it, I would put a large wager on the intake! There are some good pictures on this site,


viewtopic.php?f=43&t=4645.

[Gone Blue]

I have a '97, and I'd bet a saw buck that it will almost certainly be the lower intake manifold gasket. F'ing GM made the gaskets out of plastic I just finished this job, and while it's not pretty and could be a bit intimidating for a shade tree'r, it's well within the DIY realm.

Have you ever replaced the spider injector unit? If not, with a van of your age, I'd take the opportunity to replace it. You will have to take it out for the gasket replace anyway. You'll get better milage and performance from the new updated injectors and avoid another upper intake removal. Get it from GMpartsdirect.com they've got about the best price on it the last time I checked.

email me if you have any questions. swharris@mac.com

Thanks SW. Luckly my van is a second vehicle and a I have a new car that I drive daily. This way I can take my time fixing this leak. I am still thinking it is the intake leaking. I just wonder how I can check to be sure? Can you have an extrenal leak with a head gasket failure on these motors?

Dont know about the spider injector unit you are talking about. I bought my van this summer with 100,000 miles on it and I have maybe put 3,500 miles on it. What is the part number you are talking about?

Thanks, G.B.

[Gone Blue]

Without seeing it, I would put a large wager on the intake! There are some good pictures on this site,


viewtopic.php?f=43&t=4645.

Thanks 01safari, I have been reading the above thread and just printed off all of the pictures and your steps for changing the intake gasket. I just want to be sure my leak is the intake before I take on this repair. Thanks, G.B.

[Mr_Bowtie]

Definatly sounds like your intake leaking. If it was the head gasket it wouldn't pool up on top the intake....it would be in the oil or smoking out the tailpipe. Intake gaskets are common failures on the later model Vans.

[Shovelhead]

I'm currently working on my Van with a bad intake gasket. I pulled the spark plugs. Passenger side throught the wheel well (pull both wheels), driver side front two, through the wheel well the driverside rear most plug is gotten from under the truck.

I then filled the coolant system to the top. I pressurized the coolant system to 15 pounds per square inch. Most auto parts stores sell a tool for this. In my case, the coolant is leaking from the driver side front corner of the motor. It is also getting into the crankcase. This is evidenced by light brown chocolate colored oil, and the oil level is way too high. I just change the oil a month ago so it should have been good.

The last thing to do is to turn the motor over, clock wise, with a socket wrence on the harmonic balancer.Spark plugs must be out! Look for liquid coming out of the spark plug holes. You can also look at the spark plugs threm selves. look for gray ash color. That's from burning the coolant.

Note, is is important to pull the plugs. If the head gasket leaks coolant into a cylinder, and you try to start the motor it can go into hydraulic lock. (you can not compress a liquid), you then can bend a connecting rod, not a good thing.

Good luck,

Bruce

[Gone Blue]

I finally completed the replacement of my intake manifold gasket and got my van running last week. I wanted to thank everyone involved with this site, and especially swharris, for his help in getting me thru this project! I am fairly handy with a wrench but I am not sure I would have taken this repair on if it wasnt for this web site. It was great that my van is a 2nd vehicle and that it didnt matter when I got it back on the road. So I was able to take my time and go thru it. I purchased a complete Fel-Pro intake gasket kit and replaced all of the gaskets and o-rings on the intake and rocker covers. In addition I replaced the MAP sensor grommet and the EGR valve gasket. I also decided to throw on a new water pump, thermo stat, and all the cooling hoses while I had it a part. I am really glad that I purchased a complete set of the GM service manuals off of eBay for $24. They were very helpful and fairly easy to read. I followed the GM service manual procedure for setting the engine #1 cylinder to TDC. It made it easy to drop the distributor back in and the engine fired right up when I first started it. The van runs great and I am glad to have it back in service. I have a couple trips planned for the van this summer and feel confident that it will run great.

Thanks again to all! G.B.

[webcat]

Here's a link
viewtopic.php?f=43&t=4645&p=33269&hilit=vortec+intake+pictures#p32621

[Gone Blue]

Here's a link
viewtopic.php?f=43&t=4645&p=33269&hilit=vortec+intake+pictures#p32621

Yep, this thread was very helpful!

Thanks, G.B.