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95 Explorer head freeze plug repair


Greg C's Avatar
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02-27-05, 10:50 AM   #1  
Greg C
95 Explorer head freeze plug repair

I'm new to this site.

My V-6 has 120k and is leaking coolant from the rear freeze plug on the driver side head. The motor hasn't overheated. I haven't cleaned up the plug yet for detailed inspection; I don't know how extensive the corrosion is. I would like to avoid pulling the head to repair the freeze plug; I could do it, but it's alot of work. I'm hoping that if I cleaned it up good, and applied a sealant to the plug, such as JB weld, I would be ok. I don't think a high temp silicone would be strong enough. Any suggestions???

 
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02-27-05, 10:58 AM   #2  
The only sure cure is replacing the plug.... anything else is a bandaid that will have the corrosion grow until you have a catastrophic failure.

At the same time, since one plug is corroded to the point of leaking, I would have major concerns over the integrity of the rest of the plugs.

 
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02-27-05, 11:18 AM   #3  
Manic Mechanic
There are 2 types of replacement plugs, the original all steel disc type, which have to be driven in to swell them after removing the old one. The other type is a steel disc with a rubber plug, much on the principle of a boat transom drain plug, but instead of a lever to flip over to swell the rubber part and make it tight, there is a nut to tighten to swell the rubber part. This kind is much easier to install in tight places. Simply stick it in the hole, and tighten the nut until the plug is good and snug.

 
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02-27-05, 11:26 AM   #4  
Greg C
Posted By: mechanic The only sure cure is replacing the plug.... anything else is a bandaid that will have the corrosion grow until you have a catastrophic failure.

At the same time, since one plug is corroded to the point of leaking, I would have major concerns over the integrity of the rest of the plugs.
Yeah, I was thinking that too. Just not looking forward to pulling the heads off! While I'm at it, what else besides the other freeze plugs would you suggest?

 
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02-27-05, 11:28 AM   #5  
Greg C
Posted By: Manic Mechanic There are 2 types of replacement plugs, the original all steel disc type, which have to be driven in to swell them after removing the old one. The other type is a steel disc with a rubber plug, much on the principle of a boat transom drain plug, but instead of a lever to flip over to swell the rubber part and make it tight, there is a nut to tighten to swell the rubber part. This kind is much easier to install in tight places. Simply stick it in the hole, and tighten the nut until the plug is good and snug.
Hmmm. Think it's possible to get this one out in place and install the steel disc/rubber type? Only a few inches to the firewall...

 
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02-27-05, 04:31 PM   #6  
You will need to be able to hit it hard enough to turn it sideways so you can get a hold of it and pull it out of the hole. You will have to hit it as close to one side of the inside of the cup with a blunt punch etc. Anything sharp may just poke a hole in it . Be careful not to damage the surface of the hole.

They also make an expansion type plug that is made out of copper or brass. These last much longer than the rubber ones.

I wonder if you may have a plug that was not galvanized properly. Because if the cooling system is dirty a sludge will build up behind the plugs and cause them to rust out. But the lower plugs in the block usually go first. If you find a build up of sludge behind the plug that is the culpret and other plugs may rust through also. If it is clean behind the plug I would suspect a defective plug. If you find sludge you may want to give the system a good flush to get as much of it out as you can.

 
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03-01-05, 03:25 PM   #7  
Greg C
Hey car nut,
here's what I'm thinking.... space is tight, so I thought I'd dremel a slot in the plug near the outer edge, then use a crow's foot with a long extension to twist the plug out. What do you think?
Thanks for the inspection advise. I hope its just a defective plug! I did just put in new coolant. When I drained it, the fluid was brownish.
I did try JB weld on the plug. I was very careful about cleaning but I only reduced the leak which made me think "mechanic" is right, need to replace the plug!!

 
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03-02-05, 03:33 PM   #8  
Anyway you can get it out is fine. Be careful just don't damage the hole in the head so it will leak. It is hard to visualize the space you have to work in. If you can get it twisted sideways then you should be able to pull it out.

Brown coolant is not a good sign. Again the lower plugs usually go first. Keep your fingers crossed that it was a defective plug.

It needs at least to pull the block drain plugs and give it a good flush with the garden hose if you did not flush it already. Go back with 1/2 distilled water & 1/2 antifreeze.

 
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03-02-05, 05:07 PM   #9  
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Yeah, brown can't be a good sign. I have stuck to the factory schedule on replacing the coolant and have had the system power flushed twice prior. Hopefully it's just a defective plug...
What about running 100% antifreeze instead of 50/50? Would this minimize corrosion and not damage something else?

 
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03-02-05, 05:38 PM   #10  
Bad idea. Check any bottle of antifreeze and you will see that it is not recommended. Your water pump will be under more strain and you will not get proper heat transfer.

 
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03-02-05, 06:22 PM   #11  
I agree. 100% is not a good idea. I don't see how it will hurt the water pump but it will not cool as effectivly as 50-50. 100% water cools best but corrosion, freezing & low boiling point are what you will get.

You can easily test for EDM. (the voltage in the cooling system.) Get a digital volt meter. Set it on DC on the lowest voltage range. Put 1 probe in the coolant in the radiator and 1 on the engine block. You will get a reading from 0 volts on up. If it is over 1.5 volts it is suggested that you change coolant. The voltage slowly eats away at the metal in the as corrosion (electrolysis).
Some engines seem to rust even if the coolant is kept fairly fresh. Although I've seen this more on Chrysler products.

 
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03-03-05, 08:24 AM   #12  
Greg C
EDM test....that's an awesome tip! Thanks Car nut!
I'll likely run 70/30 coolant/water to get the most corrosion protection and stay within mfg recommendations. I'll just keep an eye on the coolant temp during the hot CA summers.
Hmmm.... I've had problems with my transfer case. It won't go into 2wd mode, if in 2wd mode, the transfer case periodically engages the front driveline. Although not confirmed yet, I believe its an electrical problem.


Last edited by Greg C; 03-04-05 at 08:02 AM.
 
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03-07-05, 04:49 PM   #13  
Greg C
I tested for EDM and only saw .4VDC.

I jumped off the bridge and pulled the heads over the weekend. The water jacket area was moderately filled with sludge. I'm having them cleaned and putting new brass freeze plugs in. The valves passed vacuum check and were still flat!! But..... according to the guy at the machine shop, the motor is running very lean (very light tan deposits). The XLT does ping when pushing it uphill. Should I be concerned? What components should I check?

 
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03-07-05, 06:28 PM   #14  
Fresh coolant usually runs about .1 to .2 volts. So keep an eye on it if you are at .4 with fresh coolant.

Maybe someone else here can help you with the transfer case problem. But I would think you should get it fixed so you can leave it in 2wd or you will probably end up breaking something.

If the heads had sludge I will bet there is more in the block. If the heads were cleaned and if you cleaned the carbon off the pistons you may have cured the pinging. If not the timing may be advanced to far. If the inital timing can be adjusted on your engine I would check it and see if it is to far advanced. If you can't adjust the timing it may be an engine management or oxygen sensor problem. Maybe someone here can help you with that.

A lean mixture, high engine temp, or spark plugs with a heat range to high can cause pinging but I would think light tan should be about right. Make sure the plugs are the right heat range for the engine. A slight ping under load on a hot engine is not much to worry about. But if it is bad or if it pings under light load you can damage the engine if you let it go.

 
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