Leaking Freeze Plug

[Knoxnate]

For the last few weeks I have been monitoring a slow leak of antifreeze that has been accumulating in a crusty form on the side of the block just below the oil filter - near the block drain. I had assumed it was the PHH and went in to replace this last weekend, however as it turns out the coolent is slowly seeping from one of the the freeze plugs. I know these are pressed in from the factory - so my question is how hard is it to relace one of these and could this plug eventually fail complely leading to rapid coolent loss?

After searching - freeze plugs, core plugs and soft plugs I have found no info or previous threads on this topic.

Thanks,

nate

 

[RavenTai]

search for freeze plug (no s) in the 80 forum, lots of posts. you can also search for "block heater"

 

[Beowulf]

Nate,

Get in there with a container of soapy water and a stiff toothbrush. Clean the area thoroughly. Slightly above the freeze plug, all around the freeze plug, and slightly (~3") below the freeze plug. Get it nice and clean so we can see what is going on and close-up post pictures. Be sure to use it if your camera has a close-up or macro setting. We need to see detail of the area.

Since you have a PHH, we know you don't have a 91-92 with the 3FE. What year is your vehicle?

-B-

 

[Knoxnate]

Beowulf,

My 80 is a 93 with 227k on it.

I will try and get in tomorrow and clean around the plug and snap some shots.

I have been doing some reading on the block heater installs - hard to understand are these holes and plugs threaded?

 

[RavenTai]

no not threaded, they are in interfearance fit, the plug is slightly bigger than the hole, when it it is pushed in the tight fit and sealant keeps it in place

 

[IdahoDoug]

I think you should carefully examine this area with a very bright light and an eye toward assuring yourself it's not coming from somewhere else. Pinhole leak from nearby coolant line, fan blowing leak from somewhere else onto this area, and head gasket all come to mind as possiblities much higher than a freeze plug. This is so rare, I've never heard of a leaking freeze plug. Any chance your block was frozen? Ever do a title search to see if it's from up north?

DougM

 

[powderpig]

Is the leak coming from the middle/bottom of the freeze plug area? Look real close to see if it is not a crack. Clean it real good and drive it for a couple of days. If it looks like a small hair line crack, replacing the plug will do no good. My hope for you is that it is not a crack. I have seen a couple of blocks cracking at this location. The easy repair is quick and painless, the best repair is a bit time consuming and a bit of a pain. So figure out what the problem is first. I do hope it is just a freeze plug. good luck robbie

 

[Knoxnate]

well I finally had the opportunity to go in and clean the area around the freeze plug. After close examination I was sure the plug was the source of the leak, until I came in and started looking at the detailed pictures I snapped of the area. The top pic clearly shows that I am dealing with a CRACKED BLOCK . This crack is so fine I couldn't see / feel it out side under the truck.

This 1993 rig has spent its life in the fairly mild climates of Arkansas and Tennessee. The PO, my formar boss, lost a hose - overheated it - and had to have the HG done about 75k ago. He did not have alot of detail about the job. I have to assume this crack is the result of that over heating and that the truck has been powering along dispite this crack for 75k.

So my question is are there options for fixing this w/o pulling the motor? And what happens if I choose to just let this ride?

Thanks,
Nate

 

[Beowulf]

I have to assume this crack is the result of that over heating and that the truck has been powering along dispite this crack for 75k.

That is a stress crack. Others, including Photoman, have had the same crack in the same place.

I'll let others give you advice on how to deal with it.
-B-

 

[IdahoDoug]

There's a process called "pinning" whereby they drill along the crack and thread in epoxy laden threaded pins. I was going to have this done on a crack in a head but the shop proved slow so I had it welded. This is not a difficult weld, though it may require some precise machining to restore the freeze plug's precision fit afterward. Perhaps stripping the intake manifold and this side of the block will allow a good welder access in situ?? Then epoxy in a freeze plug to ensure watertight fit?

DougM

 

[concretejungle]

dumb question, but would the motor need to be removed to take care of this crack? Or do you think there is enough wiggle room to remove a few parts to access it?

 

[NaterGator]

Even dumber question: cant JB weld take care of a small crack like this?

 

[RavenTai]

Even dumber question: cant JB weld take care of a small crack like this?

by itself no, maybe if you stop drilled it first then epoxied it.

 

[EricG]

Will a crack like this continue and become catastrophic? Or can you just keep an eye on the coolant levels and not worry about it?

 

[RavenTai]

cracks generally grow in any part that has stress, in this case stress could just be heating and cooling plus stress of the vibrating running engine, they will grow until they meet something to stop them like the other edge of the part, that is the idea of a stop drill, a perfectly round smooth hole can sometimes stop a crack if the stress is not to great by spreading the stress over a lager area than just the pinpoint tip of a crack, fortunately this one is out on the outside of the water jacket, were the crack near the crank bearings or cylinder walls it would be fatal to the block.

 

[MoGas]

Mine had the same problem ~30k miles. The PO had a new short block installed under warranty at that time. I would look for a place that does This type of repair as described in IdahoDoug's cracked head ordeal.

Hope this helps,
Dave

 

[AJP]

To relate a story that may be irrelevant .. but might lead to another solution(??)
many years ago a school friend threw a rod through the side of his engine block... was a Renault Dauphin (4cyl rear engine I recall) .. anyway it was a wet liner block (as were Citroen's) ... his father was a machinist and very innovative....they machined the crank. rebalanced. A new rod and piston/cylinder liner were replaced .. and he managed to get a patch on the block (not sure what or how - sorry) which he sealed both sides using a dark reddish/brown material that looked like very shiny "plastic" (was also quite hard)...the block remained leak proof for another 45000 miles of mediocre driving experience...got great mileage though...and was my first experience with radial tires (Michelin of course)- - very nice even back then.

The father worked for our large provincial Electrical utility in a generation plant... thats' where the dark red wonder material "was borrowed" from...


There are various bottles of crap that can be poured in the rad to seal small cracks...they "might" work but they have a reputation of also sealing the core of your rad. And the possibility of the crack spreading is always a consideration. Would be good to hear about any "guaranteed" repair solutions to this sort of problem... it appears nasty and I am have great sympathy for you!

 

[LuckyOreo]

Hey nate, have you found any solution to your leaking freeze plug/cracked block ? I may also have a cracked block similar to yours. Was wondering what you did.

Thanks

 

[Ppleasants]

Any update on this thread? I have the exact same issue and would love to see how a JB weld repair has held up

 

[Ppleasants]

Another bump here... I ground and a epoxied the crack with JB Weld and replaced the freeze plug but my leak has resurfaced.

@LuckyOreo and @Knoxnate any luck with repairs?