Leaking from head bolts

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Gaskacinch works pretty well, too, but Ultragray high strength RTV is kind of my go to when I don't want it to leak.
 
I've used liquid teflon and seen it dry out. I've never ever seen RTV dry out. I've seen it burn off from too much heat. That's why I recommend using the red high temp. Use whatever you want. I know what works for me.
 
Alright after pulling the valve covers and headers, I was able to thread seal all the bolts. There were three interior head bolts total that were “wet” so I am glad I did this or I would have had coolant getting into the oil.

I called it quits for the night before tackling the ***** that is the driver side header :lol:

Thanks for all the responses my lovelies
 
around the late 70s and early 80s some 318s had stickers on the valve covers about sealing bolts.
 
It has been established there are some dry and wet head bolts. Most are recommending thread tape on the wet holes.
For years, I have had very good success with Harvey Seal. Harvey™ HarveySeal is a multi-purpose, yellow thread compound that is non-hardening and non-separating. It works with everything from plain water, antifreeze, gas, oil, etc. but is very difficult to wash from your hands. Is the goto in my box when I need it to seal and stay sealed the first time.
Brand: Harvey
Set Speed: Immediate
Product Type: Soft Set
Set Type: Soft Set
Material Compatibility: ABS
Material Compatibility: Aluminum
Material Compatibility: Brass
Material Compatibility: CPVC
Material Compatibility: Copper
Material Compatibility: Plastics
Material Compatibility: PVC
Material Compatibility: Stainless Steel
Material Compatibility: Cast Iron
Withstands up to 3,000 psi on gases from -50° to +400°F and 6,000 psi on liquids from -50° to +400°F
 
I agree with some of the other guy's here, check the header bolts. Especially the outboard end holes. The factory used studs in both ends for 2 reasons, 1 they go into the water jackets, 2 they hung the gaskets on them which makes an eazy job of installing the manifold/ header.
Last fall I fired my new stroker motor and was convinced I had a cracked exhaust runner in #2 cylinder. After removing the header the port was dry, pressurized the cooling system and realized the stud was leaking. Removed the stud to find a helicoil. So most of the studs break when the manifolds are removed and consequencly the threaded holes get damaged in the repair process, which leads to in this case a helicoil or just a poor fitting stud or bolt. Either way some proper cleaning and a good shread sealant will probably fix this problem.
The reason I know this is that I found the broken stud with a broken drill bit in the center when I got the "N'" heads years ago. I had to grind out the broken drill bit and messed up the original threads requiring me to helicoil the hole. My problem is I forgot I hand threaded the new stud (after 25 years) and you now know the rest of the story.
FYI I use Cometic MLS gaskets and so far I have no head bolt leaks but I also recommend using a bit of hi temp silicone at the water holes. My stroker is built from '75 360 block from a 3500 truck MH chassis .
 
PatrioticMopar said:
Hey all,

I once again come to you seeking wisdom. The Duster project was ready to be started for camshaft break in. When doing a final prime on the oil pump, I noticed some antifreeze drips under the car. I have tracked the leak to a couple of head bolts on both sides.

This 318 motor came with the car when I bought it and had just been rebuilt. It is a 1972 LA engine. I am assuming they did not use thread sealant on the head bolts. So my questions are...

1) Does anyone know specifically what head bolts access water jackets on the 318 LA?

2) Can I remove the headers and just thread seal one bolt at a time, or do I need to tear it down to the heads to sequence the torquing?

3) Will the head gasket need to be replaced after breaking the original torque and seal on those head bolts?

thanks in advance!
Click to expand...
PatrioticMopar said:
Hey all,

I once again come to you seeking wisdom. The Duster project was ready to be started for camshaft break in. When doing a final prime on the oil pump, I noticed some antifreeze drips under the car. I have tracked the leak to a couple of head bolts on both sides.

This 318 motor came with the car when I bought it and had just been rebuilt. It is a 1972 LA engine. I am assuming they did not use thread sealant on the head bolts. So my questions are...

1) Does anyone know specifically what head bolts access water jackets on the 318 LA?

2) Can I remove the headers and just thread seal one bolt at a time, or do I need to tear it down to the heads to sequence the torquing?

3) Will the head gasket need to be replaced after breaking the original torque and seal on those head bolts?

thanks in advance!
Click to expand...
 
318 Head Bolts don't go into the water jacket. It is the end bolts on the exhaust ports that are leaking.
Use a high temp sealant.
 
451Charger said:
Define "LATER" As I recall on our 1974 Swinger 318, only the end bolts on the headers required thread sealant.
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Early 1980’s IIRC. When I see the water passages in the deck I can tell you if it has blind head bolts or not. So yes, there are blocks out there that don’t have blind head bolt holes.
 
If you have a problem head gasket can't the water 'bleed' from and adjacent water jacket opening to the head bolt? Just thinking ahead if sealing the bolts doesn't solve the problem...
 
451Charger said:
318 Head Bolts don't go into the water jacket. It is the end bolts on the exhaust ports that are leaking.
Use a high temp sealant.
Click to expand...

This is a 72 Block and when I pulled the bolts, three of them were wet with coolant... definitely in the water
 
451Charger said:
318 Head Bolts don't go into the water jacket. It is the end bolts on the exhaust ports that are leaking.
Use a high temp sealant.
Click to expand...

You been sniffin the wrong glue.
 
Having the same issues. First run of my motor and the coolant came out most of the header bolts. After doing some research, I learned the best way to install the header bolts is with the teflon thread sealant because of the bolts entering the water jackets. I put thread sealant on all of the header bolts and the bolts against the firewall still leaked. Turns out the BB header bolts I ordered from Jegs for my 383 were almost a 1/4" shorter than the originals I pulled out. That's when I removed and installed the original bolts which are a little longer, (thinking that the shorter ones do not fully seal the water jackets.) Anyway, three times a charm and I have now pulled the second from the back header bolts and done the same...hoping I have now seen the last of the coolant pouring out from my headers.
 
20 head studs seated with anti-seize. No leaks......on an '86 360 LA. Wet head bolts...that's whack.
 
I have 73 340 and it has started dripping coolant from the 2nd header bolt from the front on the drivers side, will sealant work or do I have a bigger problem. Car has not ran hot last trip the temperature stayed at 170 and I noticed the leak then.
Any help or suggestions would be greatly appreciated. Thanks
 
RustyRatRod said:
Yup. It's a random thing. And yes, I have seen some 360s with wet head bolts, but not a 340 as of yet. So far, every 318 I've seen had wet head bolts.

I would pull them one at a time and seal them with red high temp RTV and put them back and re-torque them one at a time. You'll never have them leak again. However, you'll want to drain the coolant completely and blow dry each hole with compressed air first.
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Good info
 
Michael Phillips said:
I have 73 340 and it has started dripping coolant from the 2nd header bolt from the front on the drivers side, will sealant work or do I have a bigger problem. Car has not ran hot last trip the temperature stayed at 170 and I noticed the leak then.
Any help or suggestions would be greatly appreciated. Thanks
Click to expand...
I used Permatex thread sealant with PTFE and haven’t had anymore leaking
 
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