Eliminating coolant nipple from rear housing
#1
Full Member
Thread Starter
Join Date: May 2001
Location: Kutztown, PA
Posts: 83
Likes: 0
Received 0 Likes
on
0 Posts
Eliminating coolant nipple from rear housing
I guess this question belongs here as much as anywhere.
On my race car, there is no heater core. I am also not using the stock water pump housing where the heater core return is.
Therefore, I would like to remove the coolant nipple from the rear housing and plug it rather than loop a hose around.
I have removed the nipple. For plugging, I see a couple of options:
1. Tap the hole. I like that idea most, but the area is pretty thin and I don't want to crack it.
2. Install a freeze plug. The hole appears to be 17mm and I haven't found any compatible plugs.
3. Weld something in there. I don't want to do that unless I have to. If I do go with welding, I'll fit in a threaded bung.
I just thought I'd throw this out there in case anyone else has solved this problem.
On my race car, there is no heater core. I am also not using the stock water pump housing where the heater core return is.
Therefore, I would like to remove the coolant nipple from the rear housing and plug it rather than loop a hose around.
I have removed the nipple. For plugging, I see a couple of options:
1. Tap the hole. I like that idea most, but the area is pretty thin and I don't want to crack it.
2. Install a freeze plug. The hole appears to be 17mm and I haven't found any compatible plugs.
3. Weld something in there. I don't want to do that unless I have to. If I do go with welding, I'll fit in a threaded bung.
I just thought I'd throw this out there in case anyone else has solved this problem.
#3
Full Member
Thread Starter
Join Date: May 2001
Location: Kutztown, PA
Posts: 83
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by Silkworm
Or go down to the local autoparts store, get a 5/8 heater hose cap, cap it and use a small hose clamp. Badaboom, badabing.
PaulC
Or go down to the local autoparts store, get a 5/8 heater hose cap, cap it and use a small hose clamp. Badaboom, badabing.
PaulC
Consider also that this will run at even higher pressure because, with a stock setup, when the t-stat is closed, the pump can still circulate through the heater core. In my case, the only relief will be through the t-stat's bleed hole.
Maybe I'm making this more complicated than I have to, but I've never seen anyone plug this that way. I guess it's pretty easy to test with an electric pump .
#4
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,829
Received 2,596 Likes
on
1,844 Posts
the early cars had a screw in hose barb, or they had a bolt to block it off. mazdacomp will know what it is, you will have to thread your housing for it though
mike
mike
#7
Rotary Enthusiast
Join Date: Apr 2001
Location: North Hollywood, Ca USA
Posts: 1,289
Likes: 0
Received 0 Likes
on
0 Posts
I have done this three different ways on three different engines. best and last one I tapped out the hole to a pipe thread and installed a threaded plug. I have also filled the hole with A/B epoxy and I have used the rubber cap and clamp. all have worked without failure, but I like the security of the threaded plug.
Trending Topics
#8
Old [Sch|F]ool
The in-block pressure is typically a lot higher than the radiator cap pressure, so saying the cap pops at x PSI doesn't mean much.
I went a long time with a simple block off that worked very well, although it was a bit heavy. It was a 2" length of heater hose clamped onto the nipple, and a pipe plug doped up with aviation sealer (the brown icky stuff that never washes off, gets everywhere, and smells awful in the process) jammed in the other end and clamped with another hose clamp.
I wouldn't trust most of those cheap parts-store block off caps... most of them are rather thin rubber that likes to blow out, because they go soft when they get hot. If you must go cap, get a thickwalled one, the kind that are like a REALLY BIG vacuum cap.
I went a long time with a simple block off that worked very well, although it was a bit heavy. It was a 2" length of heater hose clamped onto the nipple, and a pipe plug doped up with aviation sealer (the brown icky stuff that never washes off, gets everywhere, and smells awful in the process) jammed in the other end and clamped with another hose clamp.
I wouldn't trust most of those cheap parts-store block off caps... most of them are rather thin rubber that likes to blow out, because they go soft when they get hot. If you must go cap, get a thickwalled one, the kind that are like a REALLY BIG vacuum cap.
#9
Full Member
Join Date: Mar 2001
Location: Central Florida
Posts: 154
Likes: 0
Received 0 Likes
on
0 Posts
I used a Toyota part on my last race car. 86-91 Supras have a heater hose block off that is a very thick rubber cap. I held up perfectly for 5 years of racing.
I think the part number is 90339-16001 and should be about $4. I may be off with the part number, since it's been 4 1/2 years since I left Toyota.
I think the part number is 90339-16001 and should be about $4. I may be off with the part number, since it's been 4 1/2 years since I left Toyota.
#10
Full Member
Thread Starter
Join Date: May 2001
Location: Kutztown, PA
Posts: 83
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by tims
I have done this three different ways on three different engines. best and last one I tapped out the hole to a pipe thread and installed a threaded plug. I have also filled the hole with A/B epoxy and I have used the rubber cap and clamp. all have worked without failure, but I like the security of the threaded plug.
I have done this three different ways on three different engines. best and last one I tapped out the hole to a pipe thread and installed a threaded plug. I have also filled the hole with A/B epoxy and I have used the rubber cap and clamp. all have worked without failure, but I like the security of the threaded plug.
I like the security of a bolt as well. I REALLY don't want to have my cooling system blow out for something so trivial.
The only other person I've seen with a track only engine, actually looped the cooling system from the rear housing to the front. I don't want to do that.
#11
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,829
Received 2,596 Likes
on
1,844 Posts
Originally posted by sbaker25
The only other person I've seen with a track only engine, actually looped the cooling system from the rear housing to the front. I don't want to do that.
The only other person I've seen with a track only engine, actually looped the cooling system from the rear housing to the front. I don't want to do that.
mike
#13
Full Member
Thread Starter
Join Date: May 2001
Location: Kutztown, PA
Posts: 83
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by tims
I believe it was 1/2"NPT but check the size after removing the nipple.
I believe it was 1/2"NPT but check the size after removing the nipple.
Does anyone know if I am correct in believing that the only way to tap for AN fittings is going to be welding in a bung?
Thanks for all the responses. I think I'll try the 1/2" NPT. Should be easy enough to repair the cast housing if something goes wrong .
#14
Rotary Enthusiast
Join Date: Apr 2001
Location: North Hollywood, Ca USA
Posts: 1,289
Likes: 0
Received 0 Likes
on
0 Posts
on your tap or tap chart it should give the drill size for the 1/2"NPT tap and verify before using. if it is slightly larger you will be ok, if smaller drill out to correct size. I didn't have to drill, I just cut the new threads. next larger pipe size would be 3/4" NPT. sorry cast iron can't be repair very easily so be careful.
#15
Full Member
iTrader: (4)
Join Date: Feb 2001
Location: Irvine, CA , USA
Posts: 173
Likes: 0
Received 0 Likes
on
0 Posts
I tapped mine and installed an an fitting with a cap on it in case I want to/ need to use the heater at a later date. I'll have a look to see what size it was for sure but I think I used 19x1.5 so that I didn't have to drill the hole (since the wall is so thin.)
Matt
Matt
#16
Full Member
Thread Starter
Join Date: May 2001
Location: Kutztown, PA
Posts: 83
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by spigot
I tapped mine and installed an an fitting with a cap on it in case I want to/ need to use the heater at a later date. I'll have a look to see what size it was for sure but I think I used 19x1.5 so that I didn't have to drill the hole (since the wall is so thin.)
Matt
I tapped mine and installed an an fitting with a cap on it in case I want to/ need to use the heater at a later date. I'll have a look to see what size it was for sure but I think I used 19x1.5 so that I didn't have to drill the hole (since the wall is so thin.)
Matt
I am honestly a bit concerned about using an NPT thread anyway, I worry that the surrounding cast would crack when I try to tighten the plug.
#17
Rotary Enthusiast
Join Date: Apr 2001
Location: North Hollywood, Ca USA
Posts: 1,289
Likes: 0
Received 0 Likes
on
0 Posts
use the straight thread AN fitting if your worried about the NPT fitting. use some pipe dope on the npt and the AN should have a crush washer and a cap. either will work and neither needs to be tightened a great deal. remember all these fittings are aluminum.
#18
WingmaN
Join Date: Aug 2002
Location: Fort Worth Texas
Posts: 4,324
Likes: 0
Received 0 Likes
on
0 Posts
Have you ever seen a rubber freeze plug? They are a rubber cylinder with a washer on each side and a carriage bolt running through the middle. The washer on the outside is a little larger than the rubber. When you put it in and tighten the nut the washers compress the rubber and WALA! problem solved.
When I used to race Pontiacs I ran through so many blocks that all I used was rubber freeze plugs. I'd break and yanks 'em all out and throw them in the next one and go. They were mainly designed for when you have a freeze plug go out and you don't have enough room to knock a steel one in. As long as you can get the old one out all the way it keeps you from pulling an engine in many cases.
When I used to race Pontiacs I ran through so many blocks that all I used was rubber freeze plugs. I'd break and yanks 'em all out and throw them in the next one and go. They were mainly designed for when you have a freeze plug go out and you don't have enough room to knock a steel one in. As long as you can get the old one out all the way it keeps you from pulling an engine in many cases.
#23
Full Member
Join Date: Mar 2001
Location: Santa Barbara, CA
Posts: 109
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by Silkworm
Or go down to the local autoparts store, get a 5/8 heater hose cap, cap it and use a small hose clamp. Badaboom, badabing.
PaulC
Or go down to the local autoparts store, get a 5/8 heater hose cap, cap it and use a small hose clamp. Badaboom, badabing.
PaulC
There is no way I am taking my car out on the track without using a more secure solution again. Its too damn risky. Two failures in 8 track days when messing around with a $4k rebuild is too much...
-Matt
'87 Turbo II
'88 GTU
#24
Full Member
iTrader: (4)
Join Date: Feb 2001
Location: Irvine, CA , USA
Posts: 173
Likes: 0
Received 0 Likes
on
0 Posts
I just checked the tap and apparently it was a 16x1.5 not a 19x1.5 as I mentioned earlier. Best thing to do would be to check the hole with a drill bit, since I beleive mine is not in the block, but in the part of the press fit nipple that is stock. (The nipple was cut off flush with the block, but I don't know if there is still some of the nipple in there since I wasn't the one that cut it off but I'd guess there is part of it left if you said that the nipple that came out was 17mm)
I used pipe dope and a crush washer for my install.
Matt
I used pipe dope and a crush washer for my install.
Matt
#25
Has been.. hangin' around
Join Date: Mar 2001
Location: Milpitas, CA
Posts: 2,618
Likes: 0
Received 0 Likes
on
0 Posts
Agreed, but 8 days of hard racing is hard on parts, no question. Plus it's a turbo car. I need to wire a warning light for water temp so this doesn't bite me in the ***, but so far i've run 2 events, no issues. We'll see.
PaulC
PaulC