Coolant weep at head bolt.

[Jeff Balazs]

I have had a kind of odd little coolant leak at the center driver side head bolt on my truck for several months now. It is not getting any worse but it is troubling. It does not amount to much as far as volume goes but it is visible after driving it a few days. Has not effected the way the truck runs either.

My truck could probably use a valve job and that is one of the things I would like to accomplish this summer. This truck gets' driven daily and a bit of a freshening up is in order after more than 30,000 miles. I thought I would start getting parts together now. What I am wondering is if I should source another head just in case? What do you guy's think about this? Am I being overly cautious? or could a small crack have developed?

Thanks for your input and ideas.

Jeff

[JBNeal]

The shop manual service details a major tune up that includes re-torquing the cylinder head when warm.  It is possible that the head gasket has compressed due to heat cycling and the re-torque will improve gasket sealing.

 

OT I diagnosed a faltering passivation device as the pressure vessel was literally losing steam very slowly which led to copper tubing being burned instead of being cleansed of impurities...the PV had metal alloy gaskets that I found from the gskt mfgr had usable thickness specifications; once the gasket had compressed beyond specifications, then it was to be discarded.  Ultimately, I cleaned the PV, torqued the heads, and it was back in business, increasing yields from 25% to almost 100%, and increasing throughput by 500%...a week after I got that contraption back online, I got my pink slip...according to my former coworkers, I had stepped on some big toes by solving that problem in a few days that mgmt had not been able to address for years before I was hired, bless their hearts 

[Jeff Balazs]

Mr Neal;

Nice to hear from you. It's been a while. I have thought about doing what you suggest. My concern is that if it is a crack starting (?) it could make things go from tolerable to much worse in a hurry. I did go through re-torquing several times when I replaced the head gasket a couple years back. As it is right now I probably lose less than a teaspoon of coolant a week.

And I have put a bit of BlueDevil in it to see if that will stop it.

I have never heard of one of these actually leaking at this location. It is the head bolt closest to the distributor.

 

Your OT story sounds a bit familiar.?  Many years ago I was a consultant for the Navy. When I called them out on something similar they pretty much reacted in the manner.

[Plymouthy Adams]

coolant will wick at times up the bolt chamber.....all but a couple head bolts pass into the water jacket.....this occursmore frequent with those changing to head studs than with bolts.  But you can seal the threads if you wish but as to the interference of torque value on the bolt I cannot speak..with the studs torque is still at the head not the block so to speak as the studs are preset and sealed with a sealing tape when installed.

[maddmaxx1949]

I used Permatex 59235 thread sealant on my headbolts and have had good luck with it so far. As Plymouth Adams said a few of the bolts pass into the water jacket so thread sealing those particular ones is a good idea.

[cavisco1]

I had this same issue with a water pump bolt on a 3800 Buick. The Permatex thread sealant did the trick.

[Jeff Balazs]

When I put the head on I used Permatex thread sealant. I did not have any leaks until just the last couple of months.

W hat do you guys think? Is it safe to just pull one head bolt and re seal it? Or should I wait until I am ready to do a valve job?

Jeff

[Los_Control]

I would say a judgement call, no right or wrong answer. While probably may be fine, would be a chance gasket leaks after.

Maybe run a compression check on the nearest cylinders for reference. Fix the bolt then after a few days or hours drive time, check compression again.

You would at least know if you got lucky or not.

 

Have you tried re-torquing the head bolts?

[JBNeal]

After seeing a variety of failures in several different kinds of engines, I am a strong proponent of flush + coolant renewal every 3 yrs, regardless of mileage.  The coolant pH changes over time, causing damage to gaskets and castings etc.  If it's time to flush coolant, then ya can readily inspect that head bolt for corrosion and apply fresh sealant.  If the head gasket had a small leak, that could account for thread sealant erosion and the fluid observed. 

Edited May 15, 2021 by JBNeal

[Jeff Balazs]

So during my recent brain fart episode (truck crapping on itself) I decided to try and fix this weeping headbolt. It is the headbolt that is closest to the distributor. I drained the cooling system. I then removed the offending headbolt and cleaned it up carefully. I then put fresh Permatex high temp thread sealer on the threads and even put some high temp silicone on the upper section of the bolt. Torqued it down and no apparent weeping for a couple of days. But now it is back again. No worse than before....but no better either.

 

I figure that the head gasket has failed between the nearby cooling passage and this particular headbolt. I am considering having another go at it. This time using an O-ring up under the head of the bolt. To me this is a very odd little leak.....but I ought to be able to come up with a working fix for it. Anybody come across this before?

 

Jeff

[Dodgeb4ya]

Did you really really carefully clean the block threads and dry them too?

Then apply permatex #2 to the block threads and cleaned bolt?

Using long Q tips or equivalent....letting it sit over night before filling the cooling system.

I don't like the thread tape or white thread sealers...jmo.

If it's a head gasket leak I'd fix that soon.

Edited November 4, 2021 by Dodgeb4ya

[billrigsby]

4 hours ago, Jeff Balazs said:

This time using an O-ring up under the head of the bolt.

 

I would think without a groove machined in the underside of the head of the bolt,

an o-ring would just twist and turn and become a

twisty turny mess not resembling an O-ring anymore.

But, me NO engineer. ?

 

 

[DJ194950]

I tried some cotton string wrapped around the treads of the bolt covered in Permantex  heavy sealer ( Aviation sealer) which worked well on friends   Mopar flat 6. stopped the leaks on the head.

 

Just my past experience . Maybe block threads rusted or Over leaned out in the past??

 

DJ

[Jeff Balazs]

5 hours ago, Dodgeb4ya said:

Did you really really carefully clean the block threads and dry them too?

Then apply permatex #2 to the block threads and cleaned bolt?

Using long Q tips or equivalent....letting it sit over night before filling the cooling system.

I don't like the thread tape or white thread sealers...jmo.

If it's a head gasket leak I'd fix that soon.

No I didn't clean the threads in the block. I had originally used Permatex 2 on all these bolts when I put the head gasket on. For whatever reason it either didn't hold or the head gasket itself is allowing coolant to migrate over to the hole for the bolt.  As you know there is a cooling passage less than 1/2" away from these driver side head bolts.

None of the other bolts are leaking. This time I used Permatex 59214 high temp thread sealer. I feel like this should have cured or at least reduced the problem if the coolant is coming from the threads themselves. The only other way coolant can get into the space between the unthreaded portion of the bolt and the head of this bolt is for it to come from the nearby coolant passage in head gasket. If that is the case it does not necessarily mean that the rest of the head gasket is compromised.

 

[Dodgeb4ya]

Hopefully coolant then is not trying to weep elsewhere and into a cylinder.

You probably would notice it as a brief 1st start cylinder miss.

[JBNeal]

maybe this might just be an academic exercise, but after driving it around to get the engine up to operating temperature, check the leak area and surrounding areas for temperature variations with an infrared thermometer.

[chrysler1941]

Coolant leaks are easily found with a leak down tester with or without UV fluorescent dye. 

 

 

[Jeff Balazs]

So for now I decided to put some Blue Devil in and see if it will stop the weep around this bolt. I have run it for a couple of 1/2 hour sessions so far. It seems to have sealed up after the first session. I went with this for another reason as well. Towards the end of last winter my heater core started to leak a bit. I shut the heater circuit off which stopped the leak. Now that it is winter and we have been having a lot of very foggy days I need the defroster to work. So I figured maybe the Blue Devil might work for this leak as well.

So far so good. After the second session both leaks are gone. I will run it this way for a few weeks and then drain the old coolant and put fresh in. Will see how it goes.....

Jeff