Bypassed the intake heater lines but can't get the caps to stop bursting

[ngallina]

I have a 73z with round top carbs. The coolant lines somewhere behind the intake sprung a leak about 6 months. So I bypassed the lines. The problem is that I bought coolant caps from my local autoparts store and they keep bursting. I have had 3 break now. So I thought that I would just get a piece of hose and stick a bolt in the end and clamp it. This also didn't work. It just leaked no matter how tight I got it. By now most of you are thinking just take the whole pipe off. But the end of it has my temp sensor for the electric fans. So does anyone have any ideas on how to stop this from leaking. Thanks Nick

[Montezuma]

Why not just replace the hose that sprung a leak and make the system work properly?

[ngallina]

It is one of the metal pipes. The only time it would leak was when it was hot and I didn't want to stick my hand back there to find the leak.

[beermanpete]

Bolts don't make good plugs because the threads are hard to seal to and create a leak path. If you use bolts use some that have a section near the head without any threads and place the clamps on that area. Generally, long bolts will have an unthreaded section. If you need to cut them shorter.

[bluezcrazy]

I also have a 73 with this type of coolant pipes. You might think about replacing it with an earlier 240z thermostat housing. They only have a single coolant fitting instead of 3 fittings like yours. It is a smaller size fitting than the large one you have the sensor in, but I'm not sure what size it is. I can check if you want me to sometime when I'm at home?

My thermostat housing wouldn't stop leaking and when I went to get a 73 housing I found that they are NLA. So I capped off the intake manifold pipes, and sized down the coolant hose off the single fitting.

Bryce

[emptech]

What is a coolant cap? I know what a freeze plug is.

I had to modify the coolant system on a 260z I'm converting to round tops,

had to plug some of the metal lines. I machined a brass plug and silver soldered

it into the holes in the tube. I could have left a small piece of hose with a bolt

as you did but wanted to do the job right. That way the lines still look original,

they just have a blunt end where the hose used to go.

Jim

[ngallina]

These are the bypass caps that I have been buying. They didn't work for me.

http://www.oreillyauto.com/site/c/detail/DOR3/02253.oap?pt=N0262

Thanks for the help! I think I will try getting a bolt with a shoulder and cutting off the threaded portion to cap off the hose for now.

[ngallina]

Duplicate

Edited July 16, 2012 by ngallina
Duplicate

[Captain Obvious]

Is your temp sensor for the fan threaded? Maybe you could pull that entire piece of piping off the thermostat housing and simply thread your sensor directly into the housing?

Not the right size? Maybe use a brass threaded adapter to change to a different size?

[Zed Head]

With the flow path blocked your temp sensor is in a dead zone. Probably not very accurate. Could delay the fans coming on.

[Bonzi Lon]

The coolant cap on my 73 has a '15' on the end. Could that be a pressure rating? It has not leaked since Dealership installed. The rear pipe T had been flattened & soldered shut. A long, long time ago, 1980 and 11K miles now.

Bonzi Lon

[ngallina]

The temp sensor for the fans is threaded, but I am not sure of the thread size or where I could purchase the adaptor.

Zed Head, you are probably correct. The fans seam to turn on when they are supposed to, but the sensor is not in the most optimal place. Is there a better place for it?