How do I use this dang Combustion Leak Tester
 

Hey Everyone,

I'm sorry for the novice question, but hopefully some of you can give some guidance to the mega-noob that I am.

I'm investigating whether the RX-7 I bought last month is slowly heading towards a blown coolant seal. It's a 1986 FC N/A with 101,000km, bone stock. Driving to work this morning and when I got there I got the low coolant alarm. Pulled right over and turned off my engine. OEM temperature gauge showed somewhere between 1/3 and 1/2 way up, never above half though.

After letting my engine cool down, I removed my filler cap and noticed that my radiator was not full, however, my overflow tank was quite full (not overflowing, but it was quite a bit full). Using some dollar store supplies of a turkey baster and cheap screw driver I let out the bleeder screw and transferred coolant from the overflow tank to my radiator until it flowed out the bleeder hole smoothly, then I closed the screw and topped up the rest of my radiator. Probably transferred about 1 or 2 cups of coolant from the reservoir to the radiator.

As a bit of a hypochondriac, I'm panicking that I might have a blown coolant seal, but through my novice research, I've learned that the only real test to confirm that I have a blown coolant seal is an engine block / combustion leak tester.

I picked one up, but all the YouTube videos use one with a bulb that you manually pump, but mine has one with a hose that I'm supposed to connect to the car's vacuum system. This is the kit:


I don't want to mess things up more and start taking off any vacuum hoses, so thought you rotary experts might be able to guide me in the right direction. I have a shop manual, so I might be able to follow along and track down the technical names.

So I guess my questions are:

1. What vacuum hose do I unplug to plug this bad boy in?
2. I know my coolant expands when the engine starts to warm up and I'm assuming I need to wait for my thermostat to open to get a good reading, so how do I keep the coolant from expanding and contaminating the tester?

Thanks for your time and patience everyone. I always wanted to learn more about fixing my own car. Hopefully it's not via an engine rebuild.

Is your exhaust emitting white smoke? Have you flushed the coolant or replaced thermostat since you bought it?

Fancy little apparatus.
Now leave it on the bench while you pop the rad cap and start the car.
If you see bubbles then you got your answer.

No white smoke. I did have a coolant flush done right after I got it a month and a half ago, but have blasted the heat and bled the system a couple of times since then based on my mechanic's advice. I also religiously check my fluids and had just checked my rad coolant level the evening before. It wasn't right up to the cap, but a tablespoon of fluid would have topped it off. I guess if there was air in the system still, it may have been stuck by the bleeder screw, with coolant sitting on top of an air bubble?

I popped the rad cap off and started the car. No bubbles, but once the coolant started expanding and looked like it was about to start overflowing, I capped it off again. Wouldn't I need to wait for my thermostat to open prior to figuring out whether all my seals are intact? I don't have one of those fancy funnels and don't really want to spill coolant on my driveway for the neighbourhood pets.

My thermostat has not been replaced, but I'm not experiencing any overheating or overcooling. Operating temps seem to be steady between 1/4 and 1/2 up the gauge.

Thanks for the input.

I would try replacing the thermostat with a factory one,aftermarket ones are junk and go from there,should only cost around 15-20

I dunno, this all sounds pretty normal to me.

Your rad is supposed to pump into the recovery tank after you shut down and the coolant heat soaks and expands. Next time it starts up, coolant is sucked back into the rad.

Try this:
Warm up car fully, note fluid level in tank, then shut down.
Wait a while (1/2>1 hour maybe) and check level again...you'd expect it to be higher.
Don't touch the rad cap, let engine cool.
Start engine and bring up to temp again, with engine running, check level in tank...you'd expect it to be back where you started.
If so, the system is working as it should.

If you didn't see any bubbles, you are probably OK.

A full recovery tank could just be a bad rad cap.

Well damn.... I thought I would give it another go, toss a pan under the car and let a little overflow.... sure enough, there come the bubbles.

Looks exactly like every other horror story I saw.

So... any advice for a total noob? Should you all become my new best friends while I fumble my way through a rebuild.... I'm thinking I may be able to get it done by 2020. Or do you know of any good rotary shops that can do a good rebuild at reasonable prices in the pacific northwest?

Well, at least I got 1,000km of enjoyment out of it. I should look on the bright side. It's body is in beautiful shape and it does only have 100,000km on it.

..engine rebuild though... man, I'm going to need some car friends.

Does it bubble constantly from the time you start it ,or does it happen after it reaches a certain temp. If it only happens after it warms up,it could just be trapped air in the system.

I will take a video. It seems to do it right off the bat. Don't know why it didn't show up right away the first time, but it definitely started after about 30 seconds to 1 minute.

I started my car and started recording.

hmm that doesn't look good!

Yep,that don't look good at all

Thats exactly what mine does, so ya, rebuild time. Just don't let it sit a long time or else the water will start eating away at the insides. I try and drive mine at least once a week, and you can tell cause every once in awhile at first startup it runs on one rotor until it clears itself out.

Kind of what I figured... what a crappy thing to happen 1000km after buying it (think I may have been a bit bamboozled, but hey, a used car's a used car).

I'll have to check with my mechanic to see what a rebuild would run me (if he's even down with doing one). I would force myself to do it as punishment, but I am assuming the cost of the required tools mixed with the fact that I have no real experience would make it pretty stupid to do it myself and it would be a better option to just get somebody that knows what they are doing to get it going.

If any of you have some tips / previous experience / recommendations / etc. I would love to hear any suggestions.

Thank you for sharing your knowledge so far.

Thanks for the advice. I will still be sure to fire it up a couple of times a week to keep the water at bay while I sort out my next steps.... maybe I'll garage it and wait for the Canuck Buck to improve to make one of these US shop rebuilds a bit more reasonable.

Or maybe I'll decide to do something stupid like attempt a rebuild myself.... decisions to buy sweet cars are usually a lot easier than decisions about what to do with them when they don't work right.

Check out WestcoastRotary.com >On that site they may have info on guys that can rebuild.
I know that there is a guy in Alberta if that helps.(Adam @Rx7Specialties.)

If you've never been inside any type of engine before, i'd recommend having someone rebuild it, this way you'll get a warranty, and a piece of mind that someone with a trained eye knows what to look for

Granted yes it may cost more, but if you were to do it all yourself and miss something, you'd be the one tearing the engine back out and tearing it apart again, which may of made it cheaper to have a pro do it in the first place

Just my .02

That does help, thank you.

I'm taking my car to my mechanic on Tuesday, but he is about a 30 mile drive from me. He suggested that I close my rad cap, but don't fully lock it down, keep my rpms low, and keep an eye on my temp gauge while I limp it to town.

I'm sure he will confirm what we all are quite certain is happening, but are there any other tests I should request from him to assess the odds of a successful rebuild? I'm assuming pressurizing the coolant system and checking all plugs is in order, as well as a compression test on both rotors. Anything else I should be asking him to assess?

I'm fairly confident I have never overheated the engine, but I don't know about the previous owner and I've heard the temp gauge can be very inaccurate, especially if there is air in the system. As I mentioned, I have never seen it go anywhere above the half-way point (which I have learned is still above standard operating temp for an '86 OEM gauge).

I can't thank you enough for all your patience, input, and advice. A part of me me says "bail, bail, bail!!", but then I think about how sad it would be to not have it in my garage. Damn these cars are addictive.

I don't get the rad cap advice, seems like it'll just puke coolant the whole way.
Tighten the cap and anything over 13psi flows to the recycle tank and if your coolant seals are already going, 30 miles won't make much difference.

Unfortunately, there's no way of knowing what the major hard parts look like until it's apart and even worse, unlike a piston engine, there ain't no over boring...stuff's either good or it's not.

I rebuilt a lawnmower once :lol:

I might make my part of the project yarding out my engine and shoving the new one in. Should keep me cussing enough....

That's kind of what I thought too. I'll bleed out the system and top off before my journey. Chances are I was driving it with a blown seal since I bought it anyways so I'm sure it will be no worse off for the short trip.

Hopefully a rebuild doesn't set me too far back as it would be a shame to sell my ride and not be a part of this community!

Dude.. get a new Rad cap before you go..
If the car holds up and doesn't exhibit any symptoms,turn around and go home.You found the problem.

... but... the bubbles? I thought a faulty radiator cap would just pull air into the system rather than from the overflow tank. Are you thinking that the bubbles might still just be trapped air in the system?

Still have this fancy combustion leak tester to make things a bit more conclusive but need a vacuum nipple to hook it up to... heard there might be an unused one capped off hiding under the big air intake hose going to my throttle body (hope I got my terminology right).