Tying myself in knots on on possible internal coolant leak
 

I just picked up $600 worth of parts to do a full suspension rebuild for the Z and I've had the misfortune of a possible coolant leak, all after new gaskets have been installed from the injector housings up. This was not a problem prior, so it's most likely self-inflicted. Some of you might remember I went into the valley to replace a breather box gasket. Well, while I was in there I replaced the injector housing gaskets and the plenum gaskets. This ended up being an absolute DEBACLE because the disconnected fuel lines pushed a gallon or two of gas onto the garage floor and the whole house smelled like gas for three weeks. I avoided the doghouse with the wife but I go so flustered by this I forgot I had a leaky secondary vacuum actuator to replace on my passenger side. There was no torque sequence pattern for the housings, so I spiraled out and torqued them all to spec (per Marc's suggestion). I checked and rechecked all bolts several times. And I gotta say, I trust the FSM torque specs but it really didn't feel tight enough.

Well, fast forward 50 miles worth of driving later, and when I check the coolant reservoir after every small trip, I'm low about 15 milliliters of coolant, basically half a dose of a small Nyquil cup (i'm using one of those to measure how much to bring the coolant back to absolute full in reservoir). It didn't seem like it took this long to burp the system after I replaced the radiator and hoses last year. So the new injector housing gaskets did the trick of eliminating oil seepage where it used to pool between the housings and the heads but now seems like I've trade one problem for another. So I have to go back in regardless of a coolant leak because of the actuator but this really sucks.

I just replaced the oil about 50 miles ago, but now I'm thinking I'll drop it sometime this week to see if it's milky at all. I've picked up an Actron brand compression test tool and I'm going to take the car for a drive tomorrow, then check compression, because I like to expect the worst. So I'm curious how long does it normally take for these systems to burp themselves? No smoke on start up and no smoke out the pipes when I park it and idle after a trip. I have no external signs of leaking, there are no pools of coolant at the ends of the exhaust. It will weep water through the exhaust system joints on start up but it's just water that evaporates pretty quickly. The Injector housing coolant tubes and hoses get nice and warm after about a minute while the cam covers are cool to the touch after startup.

And if I have to go in to replace the injector housing gaskets again, is there a way to remove the fuel rails and lines as an assembly and lay to the side? I ask this because I depressurized the system with the relief valve and got a few tea spoons of fuel and nothing more. Moment I took the lines off the rail, I had a cup of fuel pour all over me and a garden hose arc of fuel flowing out the feed line. Never had this problem with an L98 system or my 383 miniram that needed to be depressurized prior to removing lines. Lesson learned and this job will be done out in the driveway instead of in the garage this time but just curious.

Sorry to vent, I spend more time worrying about not hurting anything than driving the car.

If your worried about an internal coolant leak, rent (autozone) or buy (harbor freight) a cooling system pressure tester. You’ll know pretty quick if the system has a leak. It will either hold pressure or it won’t. I suspect you don’t have a problem tho. A compression tester won’t help in determining an internal coolant leak at the injector housing.

As for the fuel rails, yes, the whole setup, injectors and fuel lines attached can simply be rotated back as one unit to rest on the windshield or an adjacent area. Like this....
H

https://cimg8.ibsrv.net/gimg/www.cor...19be37983.jpeg

I used a small bit of rtv around the coolant passage on the IH gaskets and never had a leak, but it might be possible that it could saturate and leak...well, more likely the oil vent hole will leak in that manner with that gasket though.

Picked up the coolant pressure test rental kit from Autozone. Pumped it to 15 psi and it slowly bled down to 10.5 psi. I found two leak points on the new coolant hoses installed last year. Tightened down the clamps even more and pressurized the system again to 15 psi. No leaks from the hoses now but the gauge drops from 15 psi to 12 and from there the needle is dropping another psi over about 45 minutes. So something is leaking in the gaskets most likely. I’ll check the heater core under the dash but highly coincidental it starts leaking when I did gaskets.

I’ll eat crow and say I should’ve taken your advice, Ccmano and used rtv smeared on the housing gaskets. I ran it by Marc and he advised not to in order for the gaskets to have the best “bite” with the aluminum but so much for that.

So I’ll pick up another set of housing and plenum gaskets and do it all over. What a PITA. Still need to do compression check.

Use the rtv sparingly. A light coat of Permatex might be better.
Theoretically, sealant shouldn’t be needed there if the sealing surfaces are flat and correct torque is applied. The reason I use it is to seal around the oil breather ports and prevent oil drawn into the intake. I don’t know that I’ve ever seen a coolant leak there unless the gasket was screwed up. Unless you did something wrong I’m more inclined to think there is a leak elsewhere.
H
: cheers:

If you have water leaking into the crankcase, it will probably show on the dip stick as small water bubbles.

Since you put the system under pressure without the engine running, and still had a leak after you found and remedied the external leaks, I would be concerned about cranking the engine for fear of water in a cylinder. I would pull the plugs and spin the engine to see if any water vapor blows out. Wouldn't be a bad time to run a compression test also.

This was my thought as well. I’ll pull the plugs and turn it over. I’m guessing due to the design of the plug wires, there shouldn’t be concern of arcing as long as I have them loose and out of the way. If no coolant in the cylinders, I’ll take it for a short trip to warm engine before the compression test. There were no bubbles on the dipstick. With the pedal to the floor this should trigger flood condition and kill the injectors or should I be pulling the INJ fuses instead? Thanks for the help on this, guys.

Pedal to the floor & white towel over the empty plug holes. It will help isolate if/where there’s a leak.
Ted

If it turns out that your injector housings are the source of your leaks. you may want to consider using Hylomar instead of RTV or Permatex.

hylomar is good stuff but if all is right, the plenum gaskets can be installed dry and shouldn't leak.

Marc has a fantastic DVD on plenum pulls and tips. You've already been baptized on the ceremonial plenum pull (it's a right of passage on the ZR-1)

take your time and make sure all the mating surfaces are straight and clean

I like to take a big machinist yardstick and check to make sure nothing has warped.

Give Marc or Jerry a call and you are lucky to have LOTS of Brotherhood of the beast in Fla if you need a hand.

Most are not only eager to help, they will surprise you.

That's what separates the Z from other marques. The crazy brothers that have bonded over the Legend and are committed to keeping it alive

Try some Jerry's gaskets, they seal up really well.

Gulp, also check for HG seepage. My LSV probably was "weeping" for about a year before it became terminal and the problem became obvious

Unfortunately, that's an "engine out" service but again, not a show stopper as the bottom end will likely be just fine.

The reason I encourage the "root cause analysis" is important.

In my case the coolant was washing the oil and the bottom of the 6 liner was scaloped out a bit.

I had a hell of a time finding my leak, and needed to use my bean a bit better and I would have saved a few expensive mod bucks

You'll get it!!! Half the battle is diving in and doing it.

I have do e the same as ccmano suggests. PERMATEX #2 around the crankcase vents and also the coolant runner that runs between the 2/4 and 1/3 cylinder runners. That’s where I had coolant leaks years ago but no longer.

If you want to eliminate a head gasket internal leak as a possible source of the leak try this. With the coolant pressure tester attached start the engine cold with no pressure indicated on the gauge. The pressure in the cooling system builds to aprox 7 lbs at normal running temps looking around for leaks. But if the pressure builds quickly to around 15 lbs the pressure is coming from one of the cylinders through the inner head gasket. If the head gasket is leaking to an oil galley this won’t show it but you will have coolant in the oil or the other way round.

I don’t remember if you blocked the coolant flow to the plenum with a plug in the top of the Injector housing coolant channel. If you did you could actually do a pressure test with the plenum off and actually watch to see if the lower IH gaskets are leaking into the intake. If they area leaking into the crankcase breather you would see oil in the coolant or coolant in the oil.

I still think however you will find your issue elsewhere.
H
:cheers:

Out of curiosity, are any of the injector housing bolt holes open into the water jacket?

I usually use Locktite 567 on threads that open into a water jacket and Anti-sieze on all others.

Just thinking about this I reread you comments about your coolant loss. You wrote:

“Well, fast forward 50 miles worth of driving later, and when I check the coolant reservoir after every small trip, I'm low about 15 milliliters of coolant, basically half a dose of a small Nyquil cup (i'm using one of those to measure how much to bring the coolant back to absolute full in reservoir). It didn't seem like it took this long to burp the system after I replaced the radiator and hoses last year. So the new injector housing gaskets did the trick of eliminating oil seepage where it used to pool between the housings and the heads but now seems like I've trade one problem for another.”

When you say “coolant reservoir” are your referring to the one down in the fender well in front of the tire? Not sure your aware of this, the coolant level in the reservoir fluctuates between a cold and hot engine significantly. When cold the level is low, as the pressure builds when hot coolant is expelled into the reservoir to a higher hot level. As the engine again cools when hot coolant is pulled back out of the reservoir to the “cold” level.

After working on the engine and opening the cooling system air has to find its way out of the system again, that can take several running cycles to fully resolve. During that time fluctuations in the coolant level, even the need to add coolant is not uncommon, all depending on how much air and where the air is in the system.

Unless you seeing evidence of coolant in other areas or oil in the coolant I’m not sure you even have a problem. Before tearing things apart again I would drive the car a couple hundred miles and keep an eye on things. You may very well find out things will stabilize. I just don’t see enough evidence here that there is a coolant leak into the engine. The pressure test showing a loss of pressure may simply be a small external coolant leak elsewhere. Again drive the car a bit more and see.
H
:cheers:

Thanks for the suggestions, guys I really appreciate it. Ccmano, I was referring to the recovery tank up high on the passenger's side. I think you are right, I need to drive the car some more. So I decided to stop being a chicken little and just drive the car today. No coolant out the pipes or smoke (I never pulled the plugs). I have noticed the bottom of the oil pan is shiny and the bottom of the ZF was shiny as well. It was not like this a few weeks ago which correlates to me going in the valley. My two leak points out the coolant hoses were down low, so I figure once I had it up to operating temp, droplets were falling into the air stream and getting carried right onto the pan. I checked the block drain tube before I put everything back together and it is functional, and I've had nothing dripping out of back.

I still need to do an oil pan bolt tighten check but the pan is dry higher up where the pan meets the block on the front but there's plenty of "wet shine" on the bottom of the pan and this was not a thing before I went in the valley. I had to move the coolant hose assembly a bit to clear the coolant tubes on the housings when I removed them and I mustve disturbed it just enough down on the lower hose. So maybe the two leak points I found were the culprits, one of the clamps was looser than I remember after I put a 7mm on it to check tightness. I will still do a compression check on the cylinders.


On a separate note: does anyone have Paul Workman's phone number they can PM me? I can't seem to get him a PM as it says it's disabled and I was trying to pay him for an actuator.