Hmmm advice for a coolant leak?

[crossing_over]

Whas happenin fellers. I bought a 99 tahoe back in september and she runs like a champ besides one thing. About 2 weeks after I got her, she started dripping coolant overnight. Started out as a small puddle about 6" across toward the front of the engine. Well, about 6 weeks ago I took off the skid plate and lower fan shrowd lookin for the drip but never could track it down. Then about a month ago I got home from work and something told me to pop the hood and take a look. So, I found a crack in the radiator about an inch and a half long right below the top hose on the driver side. I got me some JB weld and patched it up. The drip stopped. Well yesterday morning I noticed a small puddle once again about 6" across. I decided to fill up the radiator with coolant and see if I could find the leak. Well, wouldn't you know it did not leak all day yesterday. I got up this morning to go to work and there was a damn puddle about 2 foot across. I looked at the radiator where I patched it and it was dry so I figure that's holding up. I let it run for a sec so I could keep an eye on my water pump and it seems to be doing fine (i think a new one was put on before I got it). Anyhow, I'm going to take a look and see what I can find this afternoon. As much as I didn't want to (worried something would cease), I had to drive her to work this morning. Seemed to run perfect and stayed cool.

Are there any hoses that are known to need replacing toward the front of the engine around the radiator? It's so close to the front of the engine that I don't think it would be the IMG.

 

[41racing]

If it's a 5.7 it's most likely your intake gaskets. Look at the intake where it meets the block on the drivers side.

 

[tim@sp]

agreed with the intake gaskets...

 

[treepete]

hey, and welcome..

umm. I think that finding a leak aroud the rad itself may betough. unless its realllly leaking.
if you have a big puddle, thats a bunch. you need to actually catch it in the act of leaking.

Have you tried pressurizing the system at all and look around the rad that way? also, get the truck good and warm, and park it on an incline and let it idle then turn it off.
any fluid that has collected on the radiator lower support rail thingy will roll off the back and be easily spotted. you may have a leak alog sde of the radiator, where the metal part meets the plastic part.
if you dont see coolant leaking from anywhere the radiator, then I gotta say check the lower intake manifold gasket.

 

[JP422]

If you are gonna change the coolant... it might be a good idea to swap out the orange Dexcool and go w/ the standard green coolant. I've heard that the orange coolant might be causing the intake manifold gasket to fail. Anyway, I been using the green stuff for over 90k miles, and never had a problem (after changing out the leaky intake gasket and orange coolant)

 

[treepete]

im on the green as well after changing the lower intake gasket.

 

[crossing_over]

Welp, thanks for the advice. I'm gonna pick up a pressure tester thursday and see what I've got. If I can't find anything w/ it, i'm gonna take the radiator out completely and see if I can find it. If not, I guess Ill take a look at the IMG. Any tips incase I have to tackle the intake MG to make things easier? (besides not buying the plastic OEM version lol) I've done minor engine repair etc but never tackled tearing down to the damn manifold lol.

 

[mygreen98]

img is easy. dont take off the top 1/2 of manifold, it comes of as one assembly. removal/reintall of distributor is crucial. be absolutely precise on putting it back in exactly where it was. i use paint on the intake where it meets the dist shaft base and a mark on the firewall for rotor alignment. good luck

 

[JP422]

x2 that! Everything went along pretty well w/ the intake MG.. but the distributor screwed me up. I didn't mark it properly and that caused stumbling (kinda felt like a engine w/ timing belt off by one tooth) Ended up towing to a nearby dealer and had him fix it. Embarrassing... but oh well, ran like a champ after... and no more leaks.

It's just a bunch of easy steps... nothing crazy hard. I also agree and recommend swapping out the heater hose adapter too... crap part.

Another suggestion.. while the coolant is drained... might want to reaplce water pump and thermostat if it's been a while. Just preventative maintenance.

Good luck!~

 

[treepete]

I agree on the water pump and thermostat call. also, dont take the plastic intake off unless you have a leak there. its just wasted money. I think the plastic one is about 89 and the alum replacement is 300+$ you can see the removal together of the upper and lower intakes. unbolt everything and flip it off to the side. this old thread has the blow-by-blow.
http://www.tahoeforum.com/showthread.php?t=6663

let us know what you decide/ do.

 

[crossing_over]

Well I've checked everything before I start. No coolant in the oil. No rusty sh!t on the filler cap. So I'm going to start taking the radiator off and check that beast. Will check in sometime today or Saturday.

 

[treepete]

Well I've checked everything before I start. No coolant in the oil. No rusty sh!t on the filler cap. So I'm going to start taking the radiator off and check that beast. Will check in sometime today or Saturday.

yep. take it out, plug all the line receivers, and toss it in the bathtub and pressurize it to about 17-20lbs. you'll see bubbles ( I hope)

I hope its just the radiator failing and not the intake gasket.

keep us posted.

 

[crossing_over]

yep. take it out, plug all the line receivers, and toss it in the bathtub and pressurize it to about 17-20lbs. you'll see bubbles ( I hope)

I hope its just the radiator failing and not the intake gasket.

keep us posted.

Yeah hell I went to oriellys and autozone today to get a pressure tester and neither carry them in store anymore. I suppose they don't want you to find a leak/fix a leak and want you to buy a whole new one ) . I don't think it's the IMG. A mechanic buddy of mine come over and looked @ her and he has one of those LED flashlights. That thing lit up my engine bay and we found a hose that's dripping from the connection. It's between the AC pully and the alternator. So I'm gonna get another hose and replace it and fix/replace the tanks on the radiator and see where I stand. That's going to be my project for tomorrow morning.

 

[treepete]

its a hose?

well even better then. just as long as its not looking like this, your good.

 

[crossing_over]

its a hose?

well even better then. just as long as its not looking like this, your good.

yeah i'm pretty sure. I couldn't see that dampness beforehand and when he shined that LED flashlight down there I could see it pretty well.

 

[crossing_over]

Well. The radiator had another crack in it. I was going to just patch it but my mom told me to go buy a new one. She said if it's cracking, its wore out and aint no point in trying to patch it together. I told her I was not goin to pay for a new radiator if I could fix the one I got. She said "Fine. I'll buy one for it since your so damn hard headed." So, basically, I'm not goin to argue with her over that lol. I heard some of yall are running radiators from radiatorbarn.com . There are 3 different ones that come up for the 5.7. Which are yall running? I got my eye on the one for $142 but I don't want to buy it and it not be a good one.