1998 Chevrolet Blazer



September, 19, 2010 AT 6:55 PM

Transmission problem
1998 Chevy Blazer 6 cyl Two Wheel Drive Automatic 138000 miles

I have a 98 Blazer 4dr 2wd.

One week ago I noticed that I had what I thought was a transmission leak. A few weeks before noticing the leak I had dropped the pan and replaced the filter / fluid. I also noticed that my coolant reservoir was low so I added coolant to it.

I have been keeping a metal tray under the vehicle to monitor the tranny leak until I can get it to a shop to find the seal that is leaking (this is one job I just don't trust myself to do.) Today I checked my transmission level as I always do and noticed that my coolant was down to the bottom of the reservoir again.

Could this be a coincidence? Could this be a faulty radiator?

The fluid from the transmission seems to be leaking at the bell, it's hard to tell if they are getting mixed.


10 Answers



September, 24, 2010 AT 7:08 PM

1st thing is 1st. Lets start with one leak-coolant. Check the passenger floor for dampness. If its wet, then the heater core is no good. If its dry, then it may be the lower intake gasket which is common. Dont rule out something simple like a radiator hose, or radiator. Those components will usually leave a residue around the leak, and drip enough to puddle on the ground. If you cant find any leaks, I suggest buying a coolant pressure tester available at any parts store (usually between 80-120$) and you hook it up to your radiator as you would any radiator cap. This puts pressure in the system, and helps when locating coolant leaks.



September, 24, 2010 AT 9:25 PM

Thank you for the response. I did in fact trace the coolant back to the lower intake manifold gasket on the drivers side front. Luckily I haven't had any coolant and oil mixing to cause any visible changes in the fluid. I purchased a set of Felpro gaskets to do the job, have the tools that I need and a complete set of service manuals to give me all of the sequences and torque specs.

I do wonder one thing. The gasket set did not come with gaskets for the front and rear of the block, just the left and right set that go over the cylinder heads, and all of the gaskets for fuel lines, distributor, and upper intake. It also came with a tube of black RTV. Should I just use that sealant on the front and rear? I also purchased some Indian Head shellac compound for the lower gaskets. Should I apply the shellac or just drop them in after cleaning things up?

As for the transmission: What seemed to happen is that the coolant was picking up enough oil and dirt off of the back of the engine etc to smell at first. Or it could have just been oil that I picked up off of the parking space the first time that mixed with it. My concern for the tranny aren't really there, but I do have it a little over filled. I can just siphon it out, yes?

Thank you!



September, 24, 2010 AT 9:40 PM

If its only a little over filled, dont sweat it, if its quite a bit over, then remove your tranny cooler line, and drain some fluid out. (Passenger side of radiator)

as far as the intake goes. You make the gasket for the front and rear. The tube of rtv they gave you throw out! I use this stuff called " the right stuff" gasket maker. Its a very good silicone. Not sure who makes it, but im sure if you google it you can find out. Get it in the cheese can. You press the end of it, and it comes out like that cheap cheese in the supermarket. Make a thick bead about 1/4" tall and as wide as the block. Also push it right into the corners of your new gaskets.

Make sure all surfaces are down to bare metal. Spray brake clean on a rag, and wipe clean before you do anything. I never put anything on a gasket, unless I absolutely need to. If I do, I use a small about of " the right stuff" and smear it with my finger so its as flat as possible. Its only purpose is to keep the gasket from sliding, not to seal it. When your ready to put the lower intake on, be careful. It has to be put on almost with a surgeons accuracy. Once in place start all bolts by hand. Then proceed to torque specs.



September, 30, 2010 AT 8:45 PM

Thanks again!

I have another issue. I was successful in replacing the gaskets. I took the car for a ride to check on things, probably a 12 mile drive. About three quarters of the way home I noticed that my heater wasn't blowing as hot as it used to. The coolant was replaced and looks fine in the reservoir, so I don't suspect any leaks. (Its raining and dark out, can't see anything. Have to check my drip pan in the morning to verify the repair or " repairanoia!&Quot; haha)

I didn't " burp" the coolant when I refilled it, did it on a flat driveway too. I also didn't run the heat to open the check valve. Could air in the system cause that? Should I go back, open the cap, burp, and run the heat to open the valve?

-heater valve sounds as if it is opening when I change the dial from cold to hot.

-no drip from heater core

-vacuum tubes are all okay.

-air is warmer, just not HOT like it was

-noticed that the temp gauge didn't go past 1/4 of the way.



October, 1, 2010 AT 9:38 AM

Glad everything went well for you. I would run the truck with the cap off at idle for a while, keeping an eye on the coolant level, and adding as necessary. Also, if you havnt already, I recommend throwing in a thermostat. They are easy, and cheap. And a VERY important part of your cooling system. Let me know the results.



October, 1, 2010 AT 8:57 PM

Will do. I was kinda suspecting the thermostat as well, it's not getting up to 195 on the gauge at all. I have never heard of one not allowing the engine to get warm enough but I am sure that it has happened! I would imagine that it would still make temp even on a ten mile drive. I guess that they can get stuck any time, and in any position.

I'll let you know how it works out! Thanks, Mike!



October, 1, 2010 AT 11:19 PM

Ive seen really wild things happen with s-10s. For example, a 1994 (old body style) has 2 knock sensors, one on the back of each cylinder. They have 2 coolant temp sensors. 1 for the computer (the little one on the lower intake manifold) and another for the gauge that is on the driverside of the engine, between the exaust manifold. Looks identical to a knock sensor. I did an engine swap in one of these, and everything was fine. Except the temp gauge said it ran 30 degrees cooler than it actually was. Sure enough, when transfering the sensors from the old engine to the new engine, they had a plug where the temp sensor (for the gauge) would go, on the driver side of the engine. I put the knock sensor in that spot, and the coolant sensor in the back of the head-where the knock sensor would go. Keep in mind the knock sensors, and the coolant sensor for the gauge are IDENTICAL! That was also on a 1994, it has changed since then. But that goes to show that these things arent as simple as everyone thinks.

Back to the subject, your truck doesnt have any air-bleeders on the upper coolant tube like a 3.1, 3.4, 3.8 liter engine. The air will be pushed out by the waterpump. You said your air is only warm, not hot. It should be hot. Change the thermostat, and while your in there, use a garden hose, and flush out the system. Use a drain pan of course. 1st flush the radiator, remove the lower radiator hose from the water pump, and remove the upper radiator hose, blast water through the radiator through the upper radiator hose. Make sure you have adequate flow out of the lower hose. The block usually never clogs up, but its a good idea to flush that out as well. After that, undue both hoses that goe to your heater core (they are located on the firewall one above the other) make sure u have adequate flow through that. At this point, make sure you change your thermostat. Should have no more problems. This process, along with replacing the thermostat should take no more than 1 hr. I feel as I am writing a book, hahaha. Let me know if this solves your problem. Good luck!



October, 2, 2010 AT 12:09 AM

I've only flushed this thing from the radiator while running the car. I will go to each component as you have instructed.

As for coolant gunking up the block. The passenger side rear coolant passage (where it stops at the manifold cover) was gunked up about 1/4 inch into the passage. I cleaned that out as well as possible.

I will take note to everything that you've instructed, I really appreciate your help, man!



October, 7, 2010 AT 2:02 PM

Thanks, Mike!

Your advice did the trick! There must have been a little bit of build-up in the heater core, it took me a couple of " pumps" to get it started, after that it was running clean!

The thermostat was stuck open too, now I'm getting up to 195 again as I should be!

Thanks for your help, sir! YOU DA MAN!




October, 9, 2010 AT 1:05 AM

Im glad to help, and im very happy everything worked out well for ya. Thanks for the appreciation, a thankyou goes along way!

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