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freeze plug blew out

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paul74

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I got about 150 miles on the rebuilt engine and noticed the tiniest of drops under the freeze plugs. The machine shop said not to worry it takes a little time for them to seat. Now I have 250 miles on it.
I was out for a short drive tonight and at a yield sign noticed a little smoke out the back and at the same time a coolant smell in the car. temp and oil pressure gauges were fine. A mile or two later the smell was more pronounced and the temp gauge began to creep up. I headed home. Bout 3 miles later the temp gauge has gone about 1/4" past the N and I suddenly hear a new sound. I pulled over and turned the car off. Smoke comes billowing out of the hood. This was at 6:30 and I had a 7:00 appointment so hitchhiked home, got other car and took off. After I was finished went back to B to see the damage. The middle freeze plug was not where it belonged. What are the chances I have not toasted this engine? Thanks.
Paul
 
Hi -First of all,core plugs should not weap if installed properly.-The problem with a sudden loss of coolant, is the temp gauge does not read accurately as it is no longer immersed in coolant and usually only reads 3/4 of real temp.However you might be lucky-all you can do is replace thecore plug and the others at the same time,making sure that the seats are nice and clean before knocking them in place-I usually put a smear of liquid metal on the seat as I am putting them in,-belt and braces-not had any leaks so far using this method.then fire it up and hope everything is ok, it will be soon apparent if not-,leave the rad cap off to start with and observe if there are any bubbles coming up through the water or the worst a fountain comes out!ie head gasket gone-you don't say what "the other noise" was that it developed?this could be more worrying!
 
Ugly. Welch plugs (freeze plugs) Should NOT leak if installed correctly. Cleanliness of the bore it goes in, with a bit of Permatex "Form-a-Gasket No. 1" around the seat first. That: "The machine shop said not to worry it takes a little time for them to seat." is bogus info. They "seat" when you whack 'em in the center, on installation!

This is now just my opinion, but: if said machine shop put your engine together, I'd be talking to the owner of the place with regard to repair of any/all damage to the engine due to improper techniques. P'raps have another shop do a teardown/inspect, as I'd not trust the first place to have done ANY of it right after this... and the bill goes to the first shop. Reciepts and a lawyer would likely be involved as well. That would be made abundantly clear to "owner number one."
 
Paul, this same thing happened to one of our racers twice this past season. Both times the root cause was a cracked head, allowing the cooling system to over pressurize and blow the plug out of the block.
I definitely think a return visit to the machine shop is in order.
Jeff
 
Freeze plugs do not blow out if installed properly, they rust out. Agree with Jeff as well. There just may be another problem but I would replace freeze plugs properly then test coolent pressure before I started into anything serious.

I think they were not installed properly, after all this is so hi tech that the new kid is allowed to do the job. Bad idea.
 
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I think they were not installed properly, after all this is so hi tech that the new kid is allowed to do the job. Bad idea.

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Seen it over and over. LBC's are not viewed as "real" machines, rather are percieved as junk toys. "Junior" gets the "unenviable" job of fixing it. This is why I suggested a second shop do an exam, see if anything else is awry.
 
Morning Doc. Overcast and cool here today.
 
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The machine shop said not to worry it takes a little time for them to seat. The middle freeze plug was not where it belonged. What are the chances I have not toasted this engine? Thanks.
Paul

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Nonsense. Properly installed freeze/welch plugs never weep. The seat needs to be cleaned up with a scraper to make sure they seal. The factory installed them dry, but I always use a thin smear of RTV. You then whack them in the center with a 3/4" socket to seat them. They should never come out. See attached for how they should be installed.

The really bad news: the engine needs to come out to replace the rear one, if you dont want to risk it.

I'd return to the shop and raise, well, you know...

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Morning Doc. Overcast and cool here today.

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Rained all night but the sun's broken thru now. We're heading for the Clearwater LBC event!

MGB ain't ready, so Diesela gets to play out... and YES the camera is goin' too. /ubbthreads/images/graemlins/wink.gif

Hopin' to hook up with Jon and/or Rob too...
 
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The machine shop said not to worry it takes a little time for them to seat.

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Find another machine shop!
 
Thanks so much for the responses. There is only one machine shop in town. There must be others in the next closest town, its only 25 miles away. The block and head were sent out. Block boared for +30 pistons and the crankshaft reground. they were checked for cracks-magnafluxed??- but my mechanic put the engine together.

The back and middle plugs had the drips. The middle plug blew.

This mechanic exchanged the engine in my 90 vw vanagon from the pancake to a golf inline 4-it has run flawlessly for 3 years.

This happened last night. This morning I looked the car over a little and noticed coolant on the rubber mat on the passenger side of the car. How the heck did that get there??

Paul
 
Heater?
 
While the enginle was out I removed the heater and backflushed the core and put it back together. It did not leak then but I guess it could have failed. The hose connections are all outside the box so the core is the only possiblity, right?
Paul
 
I forgot to address Mike's mention of the 'noise'. My wife said it sounded like something came loose and was hitting the engine. I thought it sounded like someone was starting to shake a paint can and the ball bearing inside was just starting to loosen up, a rattle if you will.
Paul
 
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coolant on the rubber mat on the passenger side of the car. How the heck did that get there??

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Did you pressure test the core after backflushing it?
 
I recently had the exact same issues do to the person installing them thinking they just needed a little "tap". Weeping and the rear one blew out compeletly. Damage in the end was had gasket, head needing to go back to the machine shop. There is a tool developed to install the rear one without pulling the engine. Its very simple - a nut welded to a small plate and a bolt. Tony probably can describe it. I can shoot a picture as I left mine in the car so the rear wouldn't blow again. I think John Twist originally came up with it.
 
A picture would be greatly appreciated. Thank you max.
You are right Tony, my bad. I did'nt think to pressure test the core, it was not leaking when I took the heater apart. I did the work because with the defroster on I was getting debris blown out the vents. It turned out the insulation had completely dried up and turned to dust. The car was advertised as having lived its whole life in So CA. it might have. Anyway, I back flushed the core and got a full clear flow almost right away. The heater valve did have enough corrosion in it that I did replace that.
Tony, do you know what max is talking about with the rear plug repair?
Paul
 
Paul, not to scare you, but over pressurization of the cooling system can also result in a ruptured heater core. /ubbthreads/images/graemlins/frown.gif
Jeff
 
16 PSI MAX!!! Even that can rupture old, corroded plumbing.
 
Check it all, it came from somewhere.
 
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