1988 RX7 Convertible N/A with no major mods.

Hey what is up everyone?

I was hoping someone on here could shed some light on a problem I am currently having which has been a recurring one.

I have a coolant leak from the rear housing to the throttle body. At first the hose I had on there had failed and it started leaking at the bottom. So I replaced the hose and went on my merry way, and then a few weeks later I found another leak in the same spot.

I just went through replacing the hose with a different one of the same size again, and the leak is still there. I was going to go ahead and order the correct replacement hose from Mazdatrix (13-680A-N326) and hope that will fix it, but there is another concern I have.

The pipe coming off the rear housing has a small hole in the side towards the top and that is probably what is causing it to leak so quickly. Are there any suggestions anyone can give me on how to fix this? I can take pictures of it when I have the manifold off, but I have to be at work soon so I probably won't have pictures till Thursday.

I'm at my wits end. This is about the fifth time I have had to replace that hose. The hose size I'm using now is 3/8 I think. Whatever the next size up is, is too big. That line only leaks there and not along the other lines going to the t-stat neck. Could I be using the wrong kind of clamps? I'm using the kind that you screw on and not the clamp ones.

Any help is appreciated!

 

I'd go ahead and order the one from Mazdatrix as it would be the best fit, but from your description of the coolant nipple off the rear IRON it sounds like it's corroded or corroding. There's one sure fix in my mind and that is removing the nipple and drilling and tapping for a new one.

Unfortunately, that involves pulling the motor and depending on the age of the engine, pulling it apart in order to avoid metal shavings in the coolant passages clogging things up. I say depending on the age because I've seen guys pull the rear iron off only on newly rebuilt engines while keeping the block intact. This isn't possible on higher mileage engines as the coolant seals are more prone to un-seat and then you are really screwed. Maybe you could carefully cut the old one away and weld a new one on?

OR

You could possibly cut off the corroded part and then block the nipple off somehow depending on how much of the nipple you would have to remove. It really isn't necessary to get coolant to the throttle body. If the nipple isn't really corroded too bad you could simply make sure your clamp is well below the hole in the nipple with a properly sized hose.

Are you sure that is where the leak is coming from?

And the screw type hose clamps aren't as good as the spring type, seeing as the rubber on the hose will fatigue over time and compress. With a screw type you would have to constantly tighten them over time where as the spring type will continuously tighten.

 

Yea my plan is to really see how bad it is again and hopefully with the right hose and clamps I can keep it from leaking. I check it every day to see if and how much it leaks. I use a flashlight to look at the manifold and block to see if it pools up there and it does. It isn't a big leak, but I would like to have this fixed. The engine is rebuilt with about 40k on there I think. Might be in the 30s, but I'd like to keep it running until I can get a turbo swap going.

I need to have the line running to go to the BAC. I removed it one time and then put it back on and then found out you have to hold the throttle till the car is warm enough.

I'll just have to drive around carefully until I get the new hose and clamps and can figure out exactly what to do.

 

I've run into putting on hoses that just slip on and do not feel "tight as they should".It just doesn't feel like they would seal even with the clamp on.
So,What I have done is get a roll of wide Teflon tape and go around the Nipple(or whatever the hose attaches to.I did this on a Koyo RAD upper hose mount),Then put the hose on and tighten the clamp.It works rather well.I just Removed the hose on the same spot and everything was still intact.
OH,If you can find Fuel injection type clamps,use them,they hold better than worm gear clamps do.

 

That line doesn't actually feed the BAC. It looks like it does though, doesn't it?
IIRC without coolant going to the throttle body it takes a while for the thermowax to do its thing. But what do you need to hold your foot on the throttle for? Put it in gear and drive it, that's the best way to warm up a car, period.

 

And thank you for clarifying the names of those hose clamp types for me, misterstyx.

 

it only passes over the BAC to warm its housing. the thermowax will never work properly without it.

 

Oh yea I forgot it doesn't go through. Ha. But yea I got the hose but it looks like Monday will be the earliest I can do anything about this. I got those fuel injection type clamps from a friend of mine and they are the perfect size.

It's more of a convenience thing with the thermo wax, texFCTurboII.

I'll give the Teflon thing a try as well misterstyx.

One of these things has to fix this eventually.

 

Revived!


I didn't want to make a new thread about the same thing.

So the leak is back. Again. I know it is that line coming off the block. I haven't had a chance to see what happened this time but next week I should be able to. Being sick is lame when I want to work on my car. I have the right sized hose now, but maybe the clamp I'm using isn't the right one? I have the spring type clamp but it might be the wrong size. I can't say for sure, but I was wondering if anyone might happen to know that size of hose on coming from the back of the block.

Isn't it about 3/8 or so?

I'll be able to go measure it tomorrow.

 

I got sick of those spring clamps so now I just use fuel injection clamps.

 

I think the problem is the clamp. I have everything apart right now, so I just have to figure out which style and size will work for me. I might get one of each just in case. And I have to buy more coolant. Bah.

 

Well I cut the top of that pipe off, replaced the hose and clamp with new parts. Still ******* leaking. I'm not sure what else to do at this point.

 

You could just remove it and tap it for 1/4" NPT
https://www.rx7club.com/general-rota...t-iron-941657/

and then get a 1/4" NPT to 3/8" hose fitting...
JEGS Performance Products 16017 JEGS NPT to Hose Fittings & Hose

I did it with my engine in the car... I just stuck a magnetic stick down into the hole and collected all the metal shavings. hasn't killed anything yet

are you sure it's not the o-rings between your engine and your lower intake manifold? (I assume NAs have those...)

 

As far as I know, it is that pipe. I watched the coolant seep out of it today when I started my car. That write up seems to be the way to go, but I will have to see how this week plays out.

 

Cool.

Also, don't take the nipple out like that guy did... I just hit mine with a hammer a few times and then used a set of vice grips and pulled/twisted it out. It's just pressed in there.

 

That's brilliant! Never thought of that...
EDIT: That's a lot of metal! yeeeesh....

No turbocharger to get coolant to, so no o-rings and no flange.

 

Use some jb-weld. Spread it around the pipe. I fixed a busted block on a Volvo v-8 boat motor a fee years back. Still holding. Of course no high pressure on the cooling system in a boat motor. It is good stuff though. Might work.

 

I used waterweld on mine (JB weld for use underwater...) and it kind of worked.... I used that + put a vacuum cap on it and it still started leaking again eventually.

 

Success! I managed to pull the old crappy pipe out of the hole after using the vice grips and tapping it with a hammer and a couple of punches. Now I just need to tap it and seal everything up and I should be good to go! I'll post results when the process is complete.

 

just a heads up. you need to drill it to a certain size before tapping. also, an NPT tap is tapered, so don't tap it all the way in or you'll elongate the threads. see the other thread I posted for details.

 

Gotcha. I'll drill it out and then tap. I have all the stuff ready to go as well. This will be the second time I've tapped something and plus I have my dad here to help me out with it.

 

cool, I was just pointing out NPT taps are different, I've made that mistake before

also go slow and use lots of lubricant cleaning the tap often. I've heard of people going to fast and cracking the rear iron...

 

Slather the tap in vasoline. It will catch most of the metal shavings between the flutes. Everytime you back it out, wipe off the vasoline and reapply! Works quiet well. Same goes for drilling as well, if you have to drill it. Cover the bit in vasoline!

 

Update!

Everything is looking pretty good. Had a slight issue with the tap, but I found one that actually works and cuts. The other one I had was either really cheap, really dull, or probably both.

Once everything is put together, I shouldn't run into any clearance issues with the hose and the manifold, right?

I'll post some photos when I have the tap complete.

 

nope, it should be no different from stock. Is the 3/8" nipple longer than the stock one?

I only had clearance issues because I was using -AN lines and trying to route it under the intake manifold out the front.

make sure you put some teflon tape on the NPT threads.