Coolant Leak - Drivers Side 2002 QX4

[gcjazz12]

My QX4 has been leaking small amounts of coolant for several months - got a big puddle today after a quick drive around the block.

It looks like it's coming from the part that is attached to the air intake hose on the drivers side - does anyone know if this is common ? I can't see an exact leak point - but can definitely see it looks likes starting in this area - can see the green coolant on the bolt in the picture.

[Towncivilian]

Those are the throttle body coolant lines. Remove the air intake tube and pull the hoses off to ensure they're undamaged and the fittings aren't rusted to hell either. There is also a gasket for the IACV (the black cylindrical part that's secured by the two Phillips head screws) which appears to be the source of the leak - it might be worth replacing the gasket.

I found this O-ring at Courtesy Parts; see the diagram of its location (part 16076MA):



But it's an O-ring, not a gasket - so I'm not sure whether that gasket is available separately - or maybe it's not really a gasket and it's just part of the IACV assembly and just looks like a gasket.

[CanuckQx4]

There is a metal gasket AND that o-ring sealing the iacv

But the IACV has no coolant behind it to leak, so thats not the cause anyways.

Its most likely a burst/fatigued small coolant hose running to the throttle body

[gcjazz12]

What does the metal gasket and o-ring seal off if it's not coolant?

It looks like there may be a leak from somewhere below the IACV but it's not any of the hoses. I checked them and they're all good. The gasket on the IACV is a little bit crusty and green though.

There are several rectangular looking plastic pieces that run along the engine in that area not sure what they are - could they be what's leaking? You can see one right above the grouping of hoses. The one under the IACV is usually wet with coolant.

[CanuckQx4]

The gasket and o-ring seal the iacv to the throttle body, only air transfers behind it, no coolant.

The rectangular pieces youre refering to are your ignition coils, your spark plugs are just underneath those. Definitely not the source of coolant, and definitely not great to get baths of coolant

There are only 2 coolant lines into the throttle body in that area, the one in your picture and one about 5" to its right on the other side of the air intake. Chances are the hose is split and hard to see

Been quite a while since your original post, you gotta be sick of topping up the coolant by now

[00pathyse]

I have the exactly the same leak on my vg33. I was planning to seal it up with gasket sealant as the leak is not severe. I also don't see any leaks in my coolant lines and it looks like the IACV as well.

Is the IACV not controlled by coolant temp? It moves in as the engine warms up.

[CanuckQx4]

The 3.5L VQ engine is very different from the 3.3L, the 3.5L iacv at worst would have an air/vacuum leak. Its plunger moves in and out to control the idle when the throttle is closed, to let some air bypass to keep the engine running

[gcjazz12]

Here's a few more pictures. The hoses and connections look okay to me, it looks pretty green right on the ignition coil closest to the cabin. Could the ignition coil be leaking?

It's weird because I drove last night probably 30-40 miles and overnight, no leak on floor. I ran it to the store up the street tonight for a few minutes and I have leak on garage floor. The hit or miss of it has been what's kept me from taking it in. Still holding out for a simple fix, like tightening up a lose part.

[gcjazz12]

One more look underneath with a mirror - it looks like it's not the rubber hose that's leaking but the metal tube coming out of the IACV.

[Buzzman]

First of all, there is no coolant running through or around the ignition coil, so that is not your problem.
I think you found your problem though, judging from the last picture.
If it's leaking from the tube and not the hose, then you'll have to replace the IACV body.
I've recently had the throttle body assembly out of my Pathy, so I know how it's put together.
If there is a junk yard near you, then I'd go there and find a 2001-2004 model, and pull the throttle body off.
Take the IACV unit from the wrecker unit and install it on your truck. (a new one from the dealer is expensive).
However (and this is a big however) make sure you re-use the valve from your truck, and NOT the one from the wrecker unit.
Replace only the IACV metal body, and not the vale/sensor itself.
Here's why: You don't know if the IACV is any good from the wrecker unit, and you don't want to accidentally install a bad IACV in your truck.
It will blow your ECM.
Keep us posted.

[gcjazz12]

How would this do?
http://www.europortparts.com/searchitem ... _3Z91DJPIP

[CanuckQx4]

No, dont buy that.

Buzzmans wording is a little confusing, talking about the iacv body leaking/junkyard iacv etc. Forget the iacv, the iacv is UNDER the throttle body, and completely seperate, and has NO coolant barbs/ports.

The coolant barb you picture as the "leak" though, if it is indeed leaking there, could easily be swapped in an hour with a junkyard throttle body, or the old one could be cleaned and repaired, but its probably cheaper and easier to just replace.

Dont take a coolant leak so lightly, a blown headgasket because it overheated is no joke

[gcjazz12]

Yes, I am confused now - the leak appears to be coming from what's being described as a coolant barb. Which part then needs replaced?

There are no QX4's at any of the local salvage yards.

[CanuckQx4]

If the leak is infact the solid coolant hardline, you need a throttle body. Your pictures are very hard to see a clear picture of whats going on where though, drying the area and giving it a squirt of baby powder (yes sounds stupid but it cleans up with air hose, and will pinpoint the leak source much easier, old trick, google it) to verify that hardline connection into the throttle body is the leak. Its very uncommon, and there are aging coolant lines in that area which I would be much more suspicious of to being the source

The throttle body has your TPS sensor attached to the side of it (firewall side) which you would need to transfer over to the new throttle body, very easy, two 7mm bolts and the 2 electrical connectors that are big and easy to seperate.

[Buzzman]

No, don't buy that.

Buzzmans wording is a little confusing, talking about the iacv body leaking/junkyard iacv etc. Forget the iacv, the iacv is UNDER the throttle body, and completely separate, and has NO coolant barbs/ports.

The coolant barb you picture as the "leak" though, if it is indeed leaking there, could easily be swapped in an hour with a junkyard throttle body, or the old one could be cleaned and repaired, but its probably cheaper and easier to just replace.

Ok, I apologize if I confused everybody, but I've gone through the whole throttle body IACV replacement thing recently, so I'll try again:
The IACV valve sensor itself is the black round thing with the electrical connector on it.
It's held in with two screws.
The part that it's screwed into is what has the coolant lines on it. (Yes, it's on the bottom of the throttle body.).
The part that has the coolant running through it can be replaced separately. You don't need to replace the whole throttle body.
That part is held onto the throttle body with five screws.
Now, as for the TPS sensor on the side facing the firewall, please note: it is an adjustable part. If you loosen the two screws holding it in, you can rotate the sensor to get the right reading.
If you pull it off and install it on a new throttle body, you should take note of how it was positioned prior to removing it.
If you put it back in the wrong position, there'll be more problems.
I have a used throttle body on my workbench in my garage.
I'll take a couple of pics of it and post them up later tonight or tomorrow.
It should help.

[gcjazz12]

Thanks Canuck & Buzzman. What you are describing, Buzzmann, is where it looks like it's leaking. I was in there tonight looking again and took off the air intake tube to see if I could get a closer look. It definitely is crusty and looks pretty green where the IACV valve sensor meets the metal part that has the barbs - which is the part that's connected to the throttle body... Maybe it's a gasket that's leaking? I tried tightening up the two screws that seem to hold the valve sensor in place. It didn't leak today oddly, after quite a bit of driving. I'll keep an eye on it for awhile and post back if things haven't improved.

[Buzzman]

Ok, here are some pics. Hope this helps.
To fix your coolant leak, your best bet is the junkyard, if there's one close by.

[gcjazz12]

on Monday I put a second clamp around the coolant line going into the iacv - Tuesday I still had a leak.
Tuesday night I took off the air intake tube to get a closer look and it looked like the it had leaked right under the air intake where the iacv (metal part) and the throttle body connect. basically in the area of the top square of the part in Buzzman's final pic above. in Town's pics it looks like there is a gasket that goes between these two parts 16076M. My guess is the gasket has failed. I don't know if what I did was stupid or not but it stopped the leak, at least for now. If it holds I'll be happy with the solution - and if it doesn't will probably get reamed by a shop guy, however - I put JB weld around the seam where the two parts meet. It says it will hold up to 500 degrees - so we'll see what happens. But, so far no leaks.

what really freaked me out is when I didn't get the iacv sensor clip put back on tight and my qx4 was running at 1700rpms - bouncing around. I thought I really done it now... double checked everything and the sensor clip wasn't on tight - I pushed until it clicked and back to normal. It threw a P0505 code when I didn't have it on all the way.

[CanuckQx4]

JB weld wont fail if the pieces were clean. ive literally used it to fill a HOLE in an engine block. My friend was trimming his block webbing to clear a turbo on a honda engine, when he went way to far and had a pinky finger sized hole 1/2" X 2.5" in his water jacket. Regular jb weld and an overnight dry.... he was on his way, block still running. It will take your iacv heat no problem

high temp RTV would have been a much more reversible $5 option though lol, oh well kudos

[gcjazz12]

Ok so it's leaking out the other side now of the iac metal part that I was unable to reach with the jb weld. It's like 3 way connection (engine, Throttle body, iacv metal part) and I don't want to put jb weld on the engine part of the air intake. I think am going to have to take it all apart and put in new gasket. How hard is it to take off throttle body. Darn I got jb weld all over everything .. This is going to be fun

One of my concerns is marring the screws. They seem soft and not willing to turn.

[Towncivilian]

The TB is relatively simple to remove, as long as you find a proper hex bit to do so.

Where do you live? Maybe it would be simpler to bypass the TB coolant lines instead. Coolant running through the TB stops it from icing up, which may not be a problem depending on where you live.

[gcjazz12]

I'm in Ohio - so I think I'd be good in the summer months. Not so much now.

What about getting this part? I'd probably need the gasket goes between the Tb and the engine right?

http://www.ebay.com/itm/01-02-03-2001-2 ... bd&vxp=mtr

gasket:
http://www.courtesyparts.com/16293m-gas ... 08241.html

[gcjazz12]

I got the assembly off today. It was pretty wet with coolant outside of the gasket line, so for now I'm thinking maybe that was the issue. I am going to order new screws/washers and a new gasket and try to put my old TB assembly back in - if that doesn't work I have an assembly on order from a local wrecker. I was thinking how bad it might have been if coolant would have leaked into the intake holes in the assembly instead of spewing into the engine compartment. I got some great new tools today too - long hex bits and few different types of vise grips to get the screws out since they wouldn't budge with a screwdriver.

[gcjazz12]

I got a used throttle body assembly today complete with the IAC unit already attached. I'm thinking the best course of action at this point would be to install this in place of the old one - do I need to adjust the Throttle Position Sensor to match the orientation on my old TB? I don't have to actually put the old throttle position sensor on the new part I just got right?

[CanuckQx4]

if you havent touched the TPS sensor on the new (used) throttle body, dont. The calibration on those is VERY touchy, 1/16" and your way out. There is a calibration procedure that is quite easy, but would require you to own a feeler gauge set with a .002 and .006" feeler on it

Chances are though the sensor already attached is still working and wouldnt need adjusting

[gcjazz12]

This is a bit upsetting. I went to put in the new TB and there was more coolant sitting where the spark plugs are - even though I haven't run the car in a couple of days. I pulled off my oil cap and was quite disturbed.
Starting to think this coolant was coming from somewhere other than the TB assembly.

[gcjazz12]

Hopefully this is my last reply to my own post on this subject

Changed out the TB assembly and drove around town about 20 miles, turning off car and starting up again. No sign of coolant. I think it was the IAC gasket. I think I had coolant from not pinching off one of the coolant lines when taking off the old TB.

I'll post back if anything changes, but so far I got my fingers crossed