Leaky Intake Manifold/How to Drain Coolant?

[warp9pnt9]

Hello there folks.

Introduction: Back in March 2007 I bought a 1997 Chevy Blazer ZR2, my first vehicle ever. I've got good general technical skills for electronics and mechanical things, but very little to no experience with automobiles. So I'm not sure what exactly I'm looking at. But after many hours and many afternoons spent just sitting under my truck and staring at things, and then checking both my Haynes and Chilton books, and doing online searches, I'm starting to learn what's where and how it operates. I've got a physical disability so some things like strength and manual dexterity can make things slow going. But I'll be damned if I'm gonna pay someone else to break something else on my truck that I can't break myself for free. ;-)

Now on to the problems. Coolant has been slowly disappearing for as long as I've had the truck, probably longer. Well, now there's visible seepage of coolant around the intake manifold, and also I think it's dripping and making a spot under the vehicle. Time to get this thing changed, and deal with whatever damage has already been done before anything worse happens.

So far, I've gotten the air filter and duct removed, and the upper fan shroud. Took me a LONG time to even find the radiator drain plug. Took even longer to get my hands or tools in there to fiddle with it. Had to detach the lower fan shroud and move that aside, which wasn't so easy without a long flat screw driver. Eventually some coolant dribbled out, but only about 1/2 gallon. I was under the impression there's 3 gallons in the system. Not sure if I need to pull/twist that stupid plug more, or go for lower hoses, or if there's a way I can make it easier in the future?

The Haynes and Chilton books say to turn the radiator plug, drain, then open the engine block coolant drain plug(s), which a description of the plug as "under the intake manifold" and an arrow pointing to a nut that looks like it could be almost ANYWHERE on ANY vehicle. :-p So far I don't think these books are worth the paper they're printed on. ;-)

So, what's next?

[rat]

I wouldn't touch the coolant drain plugs.

I would pull the lower rad hose to drain the coolant.

Don't forget to change the oil before starting it back up.

[broken]

Hi there,

I've read that not all of these have drain plugs on the engine block. I know I couldn't find them on mine. One person said it could be knock sensor on the passenger side. I didn't worry about and just pulled the lower radiator hose. I have the same kind of drain plug that was a pain to turn so I just left it alone and just pulled the hoses.

Pull the lower hose first and let it drain as much as it can, then pull the upper hose and remove the thermostat and then some more coolant will probably come out. This should drop the coolant level plenty far enough to remove the intake manifold without making too much of a mess.

Good luck!

[warp9pnt9]

My "experience" tells me that the coolant plug on the radiator is difficult to access and open and fairly useless for draining anything. Is this why many people just suggest ignoring it and going straight for hoses?

The coolant reservoir and radiator cap area have lots of crusty looking junk. Sediment? Scaling? I figure since the coolant is being drained, I may as well flush the system. Hoses seemed good enough before on the outside, so I'll leave them be for now. Should I be inspecting the hoses for flow restricting sludge? Or just wait and worry about it after I stop all the leaking?

How to flush the system thoroughly? For now, I've got some chemical flush, but I suspect that can only do a little. Garden hose and tap water? Any relatively controlled ways to do this besides to spew on the truck chassis and the ground? (Besides buying a flush machine or going to specialized garage).

I don't want to pollute or cause major rust rot to my vehicle. If salty road slush is bad for the chassis, imagine the highly corrosive Dex-Cool, which has already eaten a hole in the pavement in 24h after a few drops! And the lower radiator hoses (one on each side, passenger and driver) empty directly on to the chassis, and from the looks any fluid will run along and hit many other things before finding it's way to the ground on either side of my drain pan. :-D

Is it enough to just dump a gallon of tap on the chassis after to wash away the coolant? Is the coolant base or acidic (pH above or below 7)? I can neutralize it with some appropriate solution if I spill it, then absorb with paper towels and toss. Don't want any neighbors *****ing about me working on my own vehicle and spilling chemicals and calling the EPA police on me. Some people tend to do that around here once in a while. I'd just plan to do containment and cleanup the way they'd do it, and leave minimal impact. :-)

Well, thanks for the input. I think I'll take some pictures of the process and diagram them so I leave behind the documentation for others.

[Chrisvich]

Actually just flushed my truck and the drain plug on my truck was on the passenger side of the lower rad... little black knob with a white plastic insert. If you take a 3.8 drive rachet and a small extension it inserts right into the white plastic plug. Only turns about a 1/4 to 1/2 turn so be careful not to snap it off. I just got it to move a little and unscrewed it by hand the rest of the way

[warp9pnt9]

Don't forget to change the oil before starting it back up.

Oh yeah, I've planned to do that and already gotten plenty of oil and a new filter. It's time to change it anyways. :) But I guess you say change it to make sure there's no coolant in it, right? I'll have to compare the old and the new and observe the differences. If there was coolant in there (likely with intake manifold gasket leaks?), it looks like what, milk shake, a little creamy? Guess I can always take a little bit of oil and coolant and mix on purpose in a small container to see what it looks like. ;)

Actually just flushed my truck and the drain plug on my truck was on the passenger side of the lower rad... little black knob with a white plastic insert. If you take a 3.8 drive rachet and a small extension it inserts right into the white plastic plug. Only turns about a 1/4 to 1/2 turn so be careful not to snap it off. I just got it to move a little and unscrewed it by hand the rest of the way


Mine's on the same side (passenger), little blue knob, but it's a flat tab that extends from it on mine. I can't see where exactly or how it's connected, but the coolant came out a small approx. 1/4" hose and flowed straight down, not touching the chassis. But only 1/2 gallon, as I mention above. :( Maybe I'm all gunked up inside, but I'll do the lower hose today.

[rat]

Some coolant will leak down when you pull the manifold. It will probably come out seperated depending on how much coolant leaks down. Oil does float on water after all.

[warp9pnt9]

Some coolant will leak down when you pull the manifold. It will probably come out seperated depending on how much coolant leaks down. Oil does float on water after all.

Right, of course. :p So that milkshake description I've read about applies to leaks while motor is running or possible shortly thereafter. Got it.

[C4Tom]

Pull the lower hose, drain as best you can into a container. Those small drains are for mechanics to charge you 2 hours labor to drain your system, not for someone trying to accomplish a job. There will still be coolant in the manifold when after you drain, that's why you change the oil when finished before you start it. Dex-cool isn't a corrosive, it becomes corrosive to engine components when left unchanged for 100,000 miles as suggested by the manufacturer. That has since changed.

On job completion, take it to a coin-op car wash with the power hose and just blast the frame real good with rinse(no soap) water. You might even pop the hood to get a bit of road dust off too. Be carful not to deluge the engine or electronics, just give it a light once over with engine off. The heat from the hot motor will dry it nicely before you are ready to leave, if you start under hood first.

[warp9pnt9]

Pull the lower hose, drain as best you can into a container.

Ahh much better. Got about 1.25-1.5 gallons worth of coolant out. Not quite half I'd say, but enough for the intake manifold work. Coolant went on the chassis, and ran along the front and came off the other side, so 2 bins were handy. Was quite breezy and coolant blew everywhere. :p I got most of it and doused the chassis with some water from a jug.

Dex-cool isn't a corrosive, it becomes corrosive to engine components when left unchanged for 100,000 miles as suggested by the manufacturer. That has since changed.

I think it said corrosive on the bottle, which is why I thought that. ;) And the little 3/4" hole in the pavement the next day reinforced that belief. :p

Anyhow, what's changed? Changing the coolant more than every 5 years or 100k miles?

On job completion, take it to a coin-op car wash with the power hose and just blast the frame real good with rinse(no soap) water. You might even pop the hood to get a bit of road dust off too. Be carful not to deluge the engine or electronics, just give it a light once over with engine off. The heat from the hot motor will dry it nicely before you are ready to leave, if you start under hood first.

Ahh good tip. I'm still wrestling with hoses, and Haynes/Chilton vastly images different than my specific vehicle. I'm somewhat at a loss as to what to disconnect, but I'll probably figure it out eventually. I'll try going at the hoses (mainly the upper radiator hose coming off the metal tube from the intake manifold... even with clamp removed it's bonded tight) with a clamp tool and a pick or precision philips head screwdriver, and some liquid soap. Never knew about clamp tools or picks to break seals until yesterday. :dopey_125 I'm just beginning to learn and teaching myself as I go. :)

Next challenging/dangerous task would be fuel system pressure relief. May as well do the fuel filter then.

[C4Tom]

Yes, GM doesn't recommend going 100,000 miles before a change anymore.

I'm not calling you a liar, but geez, coolant cutting a hole through pavement??? I'd have to see that.

It's always cool to teach yourself something. I study/read things alot and do alot more... taught myself many things by just doing it.

Have fun! :D