Coolant Leak Advice
 

So I went out to the garage to go to work, and noticed a pretty large wet spot under my 2003 Blazer. Upon closer inspection, I saw it was coolant. The truck had not been driven for two days, so the leak started while the truck was sitting in the garage. I was under the truck for some time, but I can't seem to pinpoint the source of the leak. It is towards the rear of the engine, there were a few drips on the oil pan and the transmission bellhousing. Also on the exhaust cross pipe. I checked the hoses to the heater core, they're okay. Would a bad LIM gasket cause this bad of a leak? The truck has been running just fine, no temp issues at all. Seems kind of odd that it would "spring a leak" like that while just sitting there. I plan on investigating more tomorrow, but I was wondering if anyone could shed some light on this. Thanks.

If you can get access to a coolant pressure tester it would be the best way to diagnose the leak. I've seen leaks at the intake but usually they only show under pressure.

Yeah, it looks like Auto Zone loans out pressure testers, gonna go there later today to get one. I don't know if this is a dumb question, but since you said that intake leaks usually show under pressure, is it possible the intake isn't the issue here since it was a pretty decent leak that happened while the truck was just sitting there?

Went out to the garage this afternoon to check things out, the wet spot was bigger, could also see coolant seeping around the intake on the driver's side. Spent about five hours out there tearing things down, only about half way through that. Seems like every time I start a project I end up breaking something else, so I'm taking it slow. I've already lost a socket and universal somewhere behind the distributor, so nothing's changed I guess.

Anyway, I read a few reviews online of the Felpro gasket set recommended here, and most of them say that the included sealant isn't enough to complete the job. Is this just regular silicone gasket sealant or something special? Gonna get some extra just in case.

Exactly how my LIM gasket leak showed up. It was leaking from under the AC compressor running along the top of the motor and dripping down the back of the engine.

When I used the FelPro gasket set the included tube of RTV was more than enough to seal the ends of the intake and ends of the intake gaskets.

Suggest when you get ready to re-install the intake, put the intake gasket on the heads and then set the intake into position....then use a feeler gauge to measure the gap between the block and the intake. This will tell you the minimun size of RTV bead needed. If too much is used then the intake will sit too high and the intake runners will not seal.

I just did this task about two months ago. Just keep track of where all the bolts go and how the wiring and hoses are routed. Pictures are worth 1000 words.

Good luck.

Thanks, I took a bunch of pictures before hand so hopefully that will help. Speaking of the RTV, is it necessary to wait 24 hours for it to dry before trying to start the truck?

I used felpro gaskets, heavy duty. There was NOT enough silicone to do the job. I bought an extra tube of ultra copper, good to 700 degrees, best stuff I ever used! I don't remember how long I waited before starting it, but it wasn't more then a couple hours.

Not for nothing BUT....Check your hoses to make sure they are secure. I "Thought" I had a upper manifold gasket leaking and took it down to the shop and after my mech look it over he found a hose clamp lose, he tighten it up and no more leak. It was leaking all around the manifold making it look like the manifold had a leak.

Yeah, I checked the hoses and they were all good.

Unfortunately, I threw in the towel over this one. I was working on on it for two straight days, and still didn't even have the manifold off. I needed to have the truck running again by this weekend, so I just put it all back together and took it down the street to my local shop. Only took me half an hour to put it all back together again. If I had more time I would have done it myself. I just didn't have the time and this isn't a job you want to rush through. It sucks having to pay for that labor, but they did a good job, and most importantly there's no more leaks.