Alrighty, first of all, Happy New Year everyone!

As some of you know, last year I replaced my entire engine on my 2000 Blazer with one out of an '03. Everything has been fine and dandy except a constant check engine light and my tach not working and gas gauge going funky. (When I fill it up, the gauge won't move until I'm at about half a tank).

But those I can kind of live with, but will take advice on if anyone as it.. No the weird thing going on is, this is a new used certified engine. I'm seeing brown spots under my truck in my drive way but I have checked ALL the fluids, oil, transmission, power steering, brake, coolant and everything is clean and full. I've checked the engine front, sides, and back, there are no wet spots or leaks that I can see...

What gives? Anyone have any tips? Am I missing something here? It's brown spots as if it's from an oil leak but I checked my oil four times and it's full/clean.

 

For your funky gas gauge, could be the float in the tank. Has your fuel pump assembly ever been changed? Float could be binding up..

What I do with suspect spots, is put a fresh piece of cardboard underneath with some weight on it, to not move. Once you see the spot locations, you can start to zero in on location of possible leaks.
Being in Florida, I could assume it could be condensation from the AC unit....mine empties by the front passenger tire.
Also, your muffler has a weep hole on it that could leave spots.

Just a few ideas to kick around.

 

I always park rear in, front facing out so I don't think it'd be my muffler. As far as I know, my fuel pump has never been changed so I probably SHOULD get on that, seeing as it's a 19 year old part now. It could possibly be the AC condensation making an old oil spot look new, now that I think of it, but yeah I'm going to switch where I park in the drive way because I don't have any cardboard on hand. Thanks for the advice and putting the idea in my head. It just totally bewildered me because everything on the front end is practically brand new and shouldn't be leaking anywhere.

 

Usually smell and taste is a handy things there, but depending on the area, there might be some other "biological" waste of a brown color too. So careful.
If You have the check engine on, why don't You list the codes?

 

I already know what the code is from. It's a faulty knock sensor trip because Chevy changed the engine a bit in 2003, which is the donor vehicle mine came from. My mechanic had to semi juryrig it up to get it in my car so now it trips the code. It's annoying but I don't know how to fix it besides just resetting it every so often.

 

Just wanted to come back to this;

The issue was my oil cooler lines. They were old and rusted and since have been replaced with OEM AC Delco parts.

 

That's what we like too hear, "problem fixed"

 

9/10 times it's the oil cooler lines.