Coolant Leak Solved I Think !!

[TX '90 ZR1]

Weather was nice enough a couple of weeks ago to get the "Z" out and take it for a spin. After putting it back to bed I noticed a small amount of coolant had ended up on the floor. Location was under the drivers side of front of engine. Also noticed a drip on cross member in this location.
Decided to tear into it yesterday to figure out the culprit. Removed intake filter housing and used a mirror to attempt to identify location of the leak. Nothing coming from the "nose" of the water pump, but under the drivers side of water pump looked a little too clean.
I remembered reading a post about tightening the water pump bolts, so gave this a shot. Found 1 not much more than finger tight and a couple more not tight enough.
Weather was nice today also, so got it out to test my coolant leak fix. Let it idle 'till the fan came on, ran it around a bit, parked for a couple of hours and then did it again.
I think it is fixed!! No drips, no sign of leakage found using mirror to inspect all around the water pump area.
While the "Z" was out I washed the "winter dust" off. I think it still looks great!z012818 (3).jpg

[Dynomite]

Originally Posted by TX '90 ZR1

Weather was nice enough a couple of weeks ago to get the "Z" out and take it for a spin. After putting it back to bed I noticed a small amount of coolant had ended up on the floor. Location was under the drivers side of front of engine. Also noticed a drip on cross member in this location.
Decided to tear into it yesterday to figure out the culprit. Removed intake filter housing and used a mirror to attempt to identify location of the leak. Nothing coming from the "nose" of the water pump, but under the drivers side of water pump looked a little too clean.
I remembered reading a post about tightening the water pump bolts, so gave this a shot. Found 1 not much more than finger tight and a couple more not tight enough.
Weather was nice today also, so got it out to test my coolant leak fix. Let it idle 'till the fan came on, ran it around a bit, parked for a couple of hours and then did it again.
I think it is fixed!! No drips, no sign of leakage found using mirror to inspect all around the water pump area.
While the "Z" was out I washed the "winter dust" off. I think it still looks great!

Way Ta Go

[RussMcB]

Glad you found it and it was an easy fix.

A good suggestion for locating coolant leaks more easily is to use a coolant system pressure tester. I think some places will rent them. I've owned one for decades and it is awesome. Screw it on in place of the pressure cap, pump it up to the cap's rating, then look for where it's (usually) spraying out.

[TX '90 ZR1]

Thanks Dynomite:
I am of the "find the issue" school as opposed to the "replace the part" school.
I wrenched on vintage aircraft for years and did not have the option to switch out parts to see if the problem was fixed. A lot of times our only option was to "fix it or else"

RussMcB:
I actually have one of those. Totally forgot about it. Could have probably saved myself some time.
Oh well, I like spending time with the "Z".z012618 (3).jpg

[We Gone]

I agree Fix the issue the right way

[DRM500RUBYZR-1]

Originally Posted by RussMcB

Glad you found it and it was an easy fix.

A good suggestion for locating coolant leaks more easily is to use a coolant system pressure tester. I think some places will rent them. I've owned one for decades and it is awesome. Screw it on in place of the pressure cap, pump it up to the cap's rating, then look for where it's (usually) spraying out.

Agreed, best way!
Just don't go overboard and pump beyond cap pressure unless you cherish the thought of replacing your heater core.

Marty

[RussMcB]

The Stant kit comes with an adapter to test the cap's relief pressure, too. I've run across a LOT of caps that don't hold the pressure listed on the cap.

My normal procedure is to first see what pressure the cap holds (and replace it if it's toast), then test the whole system a pound or two higher, then leave it for a while (maybe even overnight) to see if it holds.

It's nice when you start pumping up the pressure and then see a stream of coolant coming out of an easy-to-replace hose, or find a clamp that just needs tightening.

Last month my Miata had a tiny stream shooting directly onto the exhaust manifold. It was so fine (and steady), it looked like a piece of safety wire. I had to look twice to see it.

[Paul Workman]

Me too! It boils down to inductive vs. deductive (troubleshooting).

"DEDUCTIVE reasoning" begins with a general understanding of how (the system) works and narrowing it down, i.e., testing, to derive at specific conclusion.

"INDUCTIVE reasoning" (troubleshooting) begins with a certain circumstance(s) and draws some general conclusion: "Well, it could be this, or it could be that." That is what leads to "changing both this and that and hopefully the problem is solved." Or, put another way: "If this is happening, then change the (whatchmacallit and whatchmajigger)".

Coolant leaks are usually pretty straight forward. But, while we're on the subject, I'll relate a problem I had this time last year - not exactly a coolant leak, per se', but leak in the coolant system.

Anywayz....

• Coolant had run out of the overflow reservoir - about a quart worth.
• No leaking (detected) elsewhere, anywhere.
• Car ran fine before shutting it off - NO temp issues.

Checked with Marc Haibeck for some of his thoughts and to get a better scope of some possibilities as a starting point from which to deduce the cause. Like I thought, the problem has a narrow scope of possible causes...and the top of the list was head gasket (w/o any more information).

The short story is, after refilling the coolant, I went for a test drive. And, soon as I pulled back into the garage, I gave it a good once-over visual inspection and BINGO! That right angle coolant hose connecting to the left bank coolant manifold pipe was split and bulging like a tick ready to pop! And, there was a smell of coolant under the hood, and a strong light revealed a wisp of steam coming from the split in the hose. But! the coolant level in the overflow reservoir was normal for a hot motor - i.e., NOT overflowing.

Replacing the hose ended the issue.

Here's my theory: instead of drawing from the coolant overflow reservoir, air was being drawn into the cooling system, displacing some coolant(!) as the engine and coolant returned to ambient temp. IMPORTANT CLUE: Had I looked, I'd have seen the coolant level in the overflow reservoir I might have wondered why it hadn't been drawn down to the "COLD" line! (Of course that fact wouldn't have eliminated a head gasket leak, but there were no collaborating pieces of evidence to support a head gasket leak.)

On next startup/run, the normal expansion pushed coolant into the overflow reservoir. And, because coolant was not drawn back into the system, having been displaced instead with AIR, the coolant level exceeded the reservoir capacity (especially during the normal temperature spike immediately following engine shutdown) and coolant spilled out onto the garage floor.

I was puzzling over why I didn't see coolant leaking out of the rubber elbow section when the system was pressurized, and yet AIR was allowed to leak in through that same elbow instead of drawing coolant from the overflow reservoir?

Well, as a matter of routine, I always put 2-3 pellets of stop leak (powdered wood) in the system (similar to factory fill procedure on new cars too). My hypothesis is if the leak was small enough, the stop leak (wood dust) would seal the (pin-hole) leak under pressure. BUT! When cooling, there would be a slight vacuum - enough to dislodge the "seal" from the wood dust and allow air into the system, thus displacing some coolant otherwise drawn in from the overflow reservoir. NOW, on next startup, the normal expansion would push coolant into the reservoir, but there was not enough room for the expanding coolant plus the coolant that remained due to the air displacement.

So... In conclusion because the leak was tiny, stop leak prevented any tell-tail signs of a leak except for a whiff of coolant upon raising the hood immediately after shutting the motor off after it was fully warmed up (fan was running). And, the vacuum during the cool down prevented coolant from escaping. After cooling to ambient temp, any seepage from the pinhole leak evaporated in the interim before the next startup.

Apparently, that was the issue. 3000 miles including MR5 and Bowling Green and the rest of the 2017 season with ZERO return of the issues with coolant overflow seems to prove the point.

I've been fussing with cars since the late 60s - even worked in a shop while attending college where I did everything including engine overhauls and a couple of M21 and a M22 transmission(s). But, this "pin-hole" leak was a new one on me. I really appreciated being able to bounce stuff off of Marc Haibeck to get a clearer focus on what might or might NOT be the problem and how best to proceed. Is this a great club, or what??

[RussMcB]

Originally Posted by Paul Workman

<snip>..., as a matter of routine, I always put wood in the cooling system

Wait, what?!

(Sorry. I had to edit your words for dramatic effect. :-)

[Dynomite]

I will link to that


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