Tapping the heater hose nipple w/ a 3/8 NPT??
 

Any of you pro's care to chronicle the way you tap that aluminum hose connector on a timing cover?

I've done it a handful of times - usually just put the tap in w/ anti-seize and remove and clean it often. I bought a motor from someone where the entire nipple was gone and had been tapped w/ the plug being flush after it was in.

I've got a recent purchase car and the nipple has cracked twice doing it my old way - it is getting pretty short (have ground it down - although not flush).

Do most folks usually pre-drill w/ correct bit size (37/64)? I don't mind losing the hose nipple completely, just don't want to trash the timing cover.

Weld on a threaded bung.

Welcome to the broken nipple club - I'm a charter member. Only thing that I have found that helps is to use a hose clamp around the nipple to keep it from spreading while taping, and even that seems to be hit or miss. I've went to filling the complete nipple up with JB Weld, and forgetting about the pipe plug.

Ollie, that definitely is a super clean way of fixing the problem.

Why not just heli arc the end of the nipple? When you want to revert just cut the end off.

For the last 6 yrs. mine was just a hose over the end with a screw inside it with a standard
hose clamp, never been a issue for me.

67criuser, very reliable, but not very attractive.

Plugged it..

Guesses?

I'll bite! Coolant temperature sender?

Spark plug ;)

Winner, winner - chicken dinner!

We'll see how long it lasts....lol. I couldn't get a drill bit in there and I was afraid that the 3/8NPT would split it again.

i just went through this twice on my cover. the porosity seems to start the cracks. second time around i just jb welded the plug and stuck it in there. think if you cut the nipple off completely and tapped into the hsg body would be the best (for non-crack).

Don't like the heli arc idea?

It was easy to recognize. I stuck a sparkplug in a section of heater hose when I swapped out the drag car's timing cover as a temporary fix because I didn't want to take the time to find something else to plug the hole. It stayed in there for four years until I finally got around to getting something else in there. Never did leak.

I thought about running a dummy sparkplug wire to it just to mess with the other racers.

That would have been genius.

Could someone please explain why you want to do this?
Thanks,
Russ

No heater to run the hose to?

:)

Mick I put a sparkplug in one of my oval track cars and I was going to do the same thing, run a dummy plug wire to it. Oval track racers copy everything a winning car is doing. A friend of mine that ran a dirt late model once made a joke that if he won 2 weeks in a row with purple wheels the next week half the cars would have purple wheels on them .......LOL ;)

ah, okay. I wasn't thinking along those lines since this is in the street section.
But even so, wouldn't you want to run a line from the back of the head up to the timing cover, or wouldn't plugging that affect the cooling flow?

Thanks,
Russ

It won't affect the coolant flow detrimentally at all, I did it in my 428 dirt track car and have done it on all of my cars ran on dirt tracks. There is probably no form of racing or street driving that is more taxing on a cooling system than oval track racing or road racing.

Just for comparison there is no heater flow to the rear of the left head and many cars with A/C have what what is called a hot water control valve that in effect shuts off the flow to the heater core so the A/C is more efficient. That valve renders no flow exactly as blocking the heater hoses off.

Here's another way to look at it. The coolant on the driver's side of the engine passes into the the left portion of the block and flows to the rear of the block. Some of this coolant takes a short cut and enters the head through the several interconnecting holes. But every bit of this coolant is forced out of the head and into the crossover where it travels to the radiator to be cooled.

The passenger side head has the heater nipple that returns the coolant flowing through it to the water pump without going through the radiator. This is great for getting heat quickly and efficiently to the heater core, it's not so great in that none of this bypass goes through the radiator. Basically this coolant is recirculated in the engine just picking up more heat. It not only doesn't get cooled, but the normal coolant flow from rear to the front of the head is reduced. If you think about it, this bypass works extremely well for what it was designed for, but it is at the expense in cooling ability.

If the fitting on the rear of the head was connected to the crossover and not the water pump, then at least that coolant would pass through the radiator. I believe the actual result of this is coolant being returned to the radiator before it picks up additional heat when traveling to the front of the head. The temp gauge might even show a lower temp, but that's because we are allowing the front part of the head to run warmer when this flow is reduced and replaced by coolant in the crossover that has only done half its job. The question comes down to whether Pontiac with all their resources can be improved upon by affixing a couple of hoses across the engine by a back yard mechanic. My money is on the Pontiac engineers. :p

I've always used a proper-sized hose on each nipple with a pipe plug threaded into the hose and a couple of hose clamps holding everything together. They work great and last for years.

The beauties of doing it that way are that you don't have to take a chance by modifying the timing cover and that it will work on a corroded nipple.

What would happen if u plugged that nipple back on the passenger head, and also the one on the pump? So U just had the top and bottom hoses, And the stat drilled for some bypass water, the bypass still hooked up to crossover too.Would it run hotter in the heads?

I NPT tapped mine to run an adapter for AN lines for the heater. Been there darned near 20 years now.

Yeah - a lot of us run the back passenger head plugged and the heater nipple next to the water pump plugged (no coolant through the heater core). Anyone know the effects? I've not noticed any issues, but I don't run super high compression ratio engines either..

That's what I was talking about. There aren't any ill effects, other than no heater and the loss of the heater core as an emergency cooler for a hot engine. You don't need a hole in the thermostat, either, the pump can be dead-headed without ill effect.