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I'm completing a total rebuild of the engine, but my problem has been coolant leaks. The two longer manifold studs leaked. One of the water pump bolts leaked. And one head bolt leaked. I've solved all those problems using aviation gasket maker but I have one more leak that has me more concerned than the others. I'm somehow getting coolant in the oil. When I cracked open the drain plug I got a stream of coolant, maybe an ounce or two, before I saw any oil drain out. So now I've taken the front of the engine apart again. I gave the welch plug another good smack with a 13/16 socket for good measure. From what I can tell the real problem is water getting past one of the timing cover bolts and soaking through the backing plate gasket. Initially I used aviation gasket maker on the timing cover bolts, but I did not smear it on the gasket. When I reassemble everything I WILL generously coat the gasket and smear the female bolt holes with AGM before I coat the bolts and insert them. Other than timing cover bolts and the front welch plug, is there any other way for coolant to get into the oil? Is Aviation Gasket Maker the best way to seal the threads or is there a better sealant?

 

20190506_200511_1557191299345_resized.jpg.31a52da72db307457d4cc6dea54d6949.jpg  20190506_200516_1557191302184_resized.jpg.9526fbc1515bf96c477a149a6da63b76.jpg I think the hole next to the welch plug leaked.

 

 

Edited by Jocko_51_B3B

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You need to install the core plug properly..using a flat dense heavy 80% diameter driver and a 2 lb hammer... three whacks... done.

A extremely clean recess groove a must. I use J-B Weld on these type of plugs...never a leak or pop out even on HP MoPar V-8's.

Permatex Aviation #1 is a heavy thick sealer I use on threads..

Core Plug Installs (3).JPG

moparflatbrasscupsoftpl.jpg

Edited by Dodgeb4ya

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When in doubt seal all bolt threads for the head, manifolds, and front cover. May of them go into the coolant jacket. 

Also, what kind of plug is that? It almost looks like a cup type installed backwards. It should be a disc type, use with some sealant around the edge and flattened down well to seat it. I don’t seem much of a dimple in it to show that it’s seated properly. 

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I'm going to replace the welsh plug. But just in case the plug has to be replaced again for some reason, will JB Weld let go? JB Weld is pretty strong stuff. I'm sure it will seal though.

Edited by Jocko_51_B3B

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2 hours ago, Jocko_51_B3B said:

I'm going to replace the welsh plug. But just in case the plug has to be replaced again for some reason, will JB Weld let go? JB Weld is pretty strong stuff. I'm sure it will seal though.

Yes , J B will " let go " .  It is good stuff , but it can be removed . 

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I tore the engine down after running it for a short time to investigate. The bearings and journals are all perfectly fine and well lubricated. I have good oil pressure at 44psi. Hopefully the small amount of coolant that got into the crankcase migrated to the bottom of the pan and the oil pickup float stayed well above it. I doubt I have a blown head gasket since the gasket is brand new, but a compression test is a good idea.

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I just checked around for a replacement welch plug. Dorman used to make brass ones (old pn 560-023), but now apparently they only make them from steel (pn 550-023). I hope the steel plugs deform properly for a tight seal. Who knows, maybe the steel's better.

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I don't think it's the head gasket. I had only run the engine for at most one hour before tearing it down. When I put it back together I replaced the head gasket with another brand new one. What are the chances of blowing two brand new head gaskets with less than an hour's use for each one? Also, the first head gasket looks to be in perfect condition.

Edited by Jocko_51_B3B

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I checked with a local O'reilly's and they still have two brass plugs in stock so I told them to save them for me. I also asked them to check the quantity in their warehouse and they came back with a big zero so I guess it's going to be limited to steel plugs in the future. As far as the head gasket goes, I bought it in a kit so I don't know who made it. It has is a part number, V-1066-C, stamped on it so I checked the Feldpro website but it's not a Feldpro number.

Edited by Jocko_51_B3B

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I am a carpenter/cabinet maker with tons of experience and very little experience with mechanic work, so don’t take what I have to say to heart. But my experience with O’Reillys is that everything they have is crap kind of like Harbor Freight. It will work but if you need to depend on it on a daily basis it won’t stand up.  

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The brass and steel versions of the expansion plugs are made here in the US (I believe) by Dorman. Dorman is a well known and reputable company. On the other hand, I'm careful about buying parts and tools made in China. I'll gladly pay two or three times (or even more) for a quality part made in the USA that won't fail. So, as usual, Caveat Emptor. If anyone knows another source for the brass expansion plugs, pleas let the forum know.

Edited by Jocko_51_B3B

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Jocko;

I am going to say here what you probably already know. Got to be real careful with parts selection and fit for these old engines. There is a lot of rubbish out there and while a lot of it looks correct it just doesn't hold up. For head gaskets you really want Best brand. And you should probably plan on applying copper coat spray on treatment as well. I started off with a gasket set made by Felpro....a well known brand .....but their head gasket did not hold up. And believe me it was properly torqued down and re torqued a few times after a few heat cycles. When I pulled the head I a a few of my buddies who are full time mechanics look things over and their conclusion was the install was fine but the product was not. They run into this kind of problem all the time with inferior spares etc. The point I am trying to make is that it is not uncommon to find out the hard way that some of the stuff you end up using can be a real problem.

 

Unlike most of the fellas on this site I use my truck daily and it is my primary transportation. My approach to keeping my truck on the road has been to use the very best quality stuff I can lay my hands on. When I had problems with the Felpro head gasket a couple of the guys on this site suggested the Best gasket as a better solution. It has performed perfectly now for several thousand miles. When I finally get around to rebuilding my engine another Best brand gasket will be part of it. I had to find this out the hard way but that is just part of putting one of these great old trucks into use again. We are all going to make some mistakes on stuff like this and that is part of the whole experience.

Jeff

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Jeff,

I had never heard of Best head gaskets until I started this thread, but I will definitely give them a try based on your recommendation. I checked the Best website and I like their emphasis on "Made in the USA". For now I'm not sure who made my current head gasket, but I do have a question regarding head gaskets in general. Suppose a head gasket blows. I haven't seen that happen in my own experience but I imagine that a blowout in a flathead six head gasket can only open a path for coolant to flow into a combustion chamber. Since there are no oil passages between the block and the head, I see no other possibility except for coolant to get into a combustion chamber. So how does coolant get from a combustion chamber into the oil pan? If the engine is running wouldn't any leaked coolant be expelled in the exhaust? Or can it slowly seep into a combustion chamber and somehow leak past the rings when the engine is turned off? Thanks for the advice about Best.

Jocko

 

Edited by Jocko_51_B3B

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Jocko;

When the Felpro gasket on my truck let go I can assure you that I had white smoke in the exhaust and coolant in my oil. I was fortunate that it happened as I was leaving my house one morning. I just pulled it into the garage and drained everything immediately. I never bothered with trying to trace the path the coolant took to get into the oil. Instead I focused on the cause of the failure and a plan on preventing it from happening again.

Because this truck is my primary transportation I keep a fairly comprehensive collection of spares. Including a complete new set of engine gaskets by Best. After removing the head I took it and the gasket to some mechanic and machinist buddies of mine where they showed me where and why it had failed. The consensus conclusion was an inferior gasket. I was back on the road later that day and have not had any further problems with it. That was a couple of years ago. Btw I took the precaution of running fresh oil in it for around an hour. Then I did another full oil change to be certain that there was no more coolant in the oil.

Because of the design of this engine there are a few spots on the head gasket that have a very narrow sealing surface. My guess is that these areas are where 95% of all the L6 head gasket failures occur.

Hth, Jeff

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I'm going to order a couple of Best brand head gaskets. I have a couple of related questions which someone might be able to answer:

1. Since flathead 6's have unpressurized coolant systems, is it common practice to pressure test the cooling system after a rebuild? If so, what pressure would be adequate and for how long? The shop manual doesn't say.

2. What is the best sealant for sealing bolt threads? I'm considering red, gray, or black Permatex gasket sealant but I'm really not sure which would be best. I've tried aviation gasket maker on the timing cover bolt threads but when I applied 10 psi to the cooling system the ones that penetrate the water jacket leaked.

Edited by Jocko_51_B3B

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Jocko;

I know I used Permatex........think it was brown. It has worked just fine on my truck.

As far as pressure testing goes I borrowed a pressure tester from a mechanic buddy of mine and pumped it up to 12#. As I recall it held for 2 or 3 hours.....and I figured that was good enough. I did this with a freshly re-cored radiator and all new hoses, etc. It probably doesn't need to be tested that high.....I would think any leaks like you have had would show at 5#or 6#.

Hth, Jeff

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They just delivered a new "Best" brand head gasket. So my plan (at the moment) is to use the "Best" head gasket with Permatex Copper Spray-a-Gasket Sealant. I'll torque the head bolts to the high end of spec and then re-torque them with the engine hot. As far as the head bolt threads go, I'll use Aviation Gasket Maker again since the bolts are already smeared up with it. When it's all finished I'll pressure test the block and drain a little oil from the oil pan to make sure no coolant found it way down below. As far as the three bolts that surround the welch plug on the front of the engine are concerned, I'm going to try using Permatex Ultra Black (which hardens up) since these bolts don't need to be re-torqued like the head bolts do. (I also ordered a new set of "Best" timing cover gaskets because I like quality of the "Best" head gasket.) I'm wondering if it's necessary to smear up the timing cover gaskets with grease - just for good measure as I've seen other forum contributors do.

Edited by Jocko_51_B3B

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Well, I found the problem. There was a fine crack along the top of the block near the #3 and #4 cylinders. Since the intake and exhaust manifolds were not yet installed I first saw evidence of the crack when I pressurizing the cooling system and saw coolant slowly accumulate inside the #3 #4 exhaust passage on the side of the engine. How coolant got into the oil from up there I'm not totally sure. I had previously had all six cylinders re-sleeved because there was some serious pitting in the #6 cylinder wall and because all six were already .060 over . I'm sure the crack occurred during the re-sleeving work although I can't prove it. With hindsight, if I had to do this again I might not re-sleeve all six cylinders, just the badly pitted one.  Also, I would have made sure to have a magnetic particle test performed after any re-sleeving work and before putting the engine together. That might have saved me a ton of trouble and a truck load of wasted time. I'm not an expert on re-sleeving one of these engines, but I'm guessing it puts a lot of stress on the block, but what do I know?

Edited by Jocko_51_B3B
wording and clarity

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