I know squat about the F23, did some searching (even in some of the G23 stuff), but can anyone tell me whether there are water jackets or cooling passages of any type between the IM and the head?

Am trying to diag. a small mystery coolant leak and it possibly drinking coolant through the IM gasket is a last ditch theory before the head comes off, just don't know if there is a cooling connection between the two.

Motor is stock in an 02 SE, manual if that makes any difference, thanks!

 

Yes there is a coolant passage that goes from the head through the intake manifold and then into the thermostat housing. It's at the back on the passenger side (thermostat housing).

 

Thank you!

I take it that there is one passage, that is looped through the intake with an in at the head and an out at the t-stat housing?

EDIT: mean likely in at T-stat and out at head w/flow towards passenger side....

How common are problems at the gasket in that area, and is the coolant passage close enough to an intake runner or port that coolant could potentially be pulled into the intake stream?

I've hit the area hard with throttle body cleaner and got no response from the motor, but maybe the bridge in the gasket between the two is internal and not affected by the outside world?

Any other tests?

Thanks.

 

Yes the coolant passage is very close to the no.4 intake runner as shown in the image below. The passage is circled in red. That gasket shown is not a regular OEM paper gasket.

The arrows and red line shown on the intake manifold shows the coolant jacket path inside the intake manifold. It enters below the cylinder no.4 runner and exits out the side of the intake manifold where the thermostat housing is mounted.



Do you see/smell coolant on the no.4 spark plug or evident in the combustion chamber? remove the no.4 spark plug ans you should be able to tell by looking at the business end of the plug whether or not coolant is being burnt in that chamber.

 

You good sir, are awesome - your new millennium style arts-and-crafts are much appreciated!

So, in terms of the plugs, here's where the plot thickens a bit: when I pulled the plugs the other day to do a compression test (170 across the board), they looked a tad on the white side to me. Right, you're saying bingo, coolant, but there was 0 deposit or flakiness that I'd normally associate w/ burnt coolant. Rather, and this is where stuff gets bizarre, I could almost undo the plugs by hand they were in there so loose!! The ***-clown that did the last tune-up (not my ride) must have put them in a very hot head, or did not understand the concept of a crush washer. Yes, the washer wasn't even collapsed! So I associated the white with lean/hot, thinking that maybe the incorrect plug/head bond was messing w/ things, or maybe even air was getting pulled in through the threads....which might have caused some HG issues, which I'm trying to exhaust all options before ruling on...

The other thing, the #4 and #3 plugs had a little more of the normal tan to them, while the #1 and #2 were looking pretty snow-white, so given the position of the sole coolant passage, looks like it rules out that as an option...damn!

 

Yeah that is bad.... you shouldn't be able to remove them by hand.

White is definitely lean vs the other ones that are tan. Usually when I have run into coolant being burnt in the combustion chambers the spark plugs were clean and somewhat shinny. As they are pretty much steam cleaned and glazed.

Have you tried running a coolant system pressure test? We used to run this test on a cold engine and then hot if we could.

 

Yeah, I did a coolant pressure test and the pressure didn't hold with the motor off, but I think that was more to do with not having the right attachment for an ideal seal at the filler neck (I could see some bubbling where the fitting screwed into the neck past 10-15 psi). I used it more to try get a visual on any leaks, and I pushed the pressure hard (25 psi) and I couldn't get anything to blow up, all I could come up w/ external was some sweating at the rad seams, which is not bad concerning it's the original stock rad. I tried it cool, motor off; cool motor on; and then ran it through some heating cycles where I again pushed it to over 20 psi. It seemed to even out between 10-15 psi, w/ nothing except the rad seam sweat.

I'd already tried a different rad cap earlier, so just to be 100% sure in case there was a hidden leak or pin-hole somewhere, I replaced the rad, upper and lower rad hoses, t-stat and gasket, gasket where the upper rad hose comes out of the head, and a bunch of clamps for the heater hoses. In doing the heater hoses, the little arm on the heater control valve broke, and now it leaks a tiny bit, so I haven't been able to confirm if all that did anything, but it's still drinking coolant and I don't think the mini-leak at that valve (part coming tomorrow) is enough to justify the loss from the reservoir.

 

Perhaps the water pump weep hole is leaking or in rare circumstances the heater core is bad but I doubt that.

 

Thou shalt not utter such blasphemy upon this forum!

Seriously. If my car kills a heater core, it's going to be left on your porch with a bloody ransom note for your dog/cat/fish/dude-in-hole-putting-lotion-on-skin/bird/pony. Did one on a Fox Mustang and a Grand Cherokee... never again. Thank god Honda somehow makes theirs last.