ECU meltdown

[barbee6043]

I have owned half a dozen 70's mopars over the decades that came factory with ECU boxes, and I have seen the ones in the boneyards where the insulation in the backside of that unit ran out down the fenderwell. never had this occur with one I owned..
I drug home a 79 car and the ECU box's backside has melted out but still fires up and runs down the road good. just curious, why this meltdown occurs, and no doubt it needs replaced. I see people speak of the mopar chrome box as a good unit.
I know those with HEI exclaim their greatness.

 

[MoparMike1974]

Too much heat melts the coating. I have had them do this in storage. Makes a mess of everything that is near it. Last one leaked on the floor and a mouse got stuck in it and died.

 

[adriver]

You mean the stuff that just gets hot and melts?
I think it starts creeping at anything above freezing.
And just gets worse when hot.

 

[Daves69]

Too much heat melts the coating. I have had them do this in storage. Makes a mess of everything that is near it. Last one leaked on the floor and a mouse got stuck in it and died.

Not necessarily all due to heat IMO. I had two in the same box right next to each other on a shelf for several years. One leached out the other didn't.
The picture is of a '70s black and gold ECU. Notice the run out goes toward the side of the ECU at the bottom of the picture. This is how it was packed in the box. The other blue and gold ECU shows no sign of leaching at all.............

 

[barbee6043]

Not necessarily all due to heat IMO. I had two in the same box right next to each other on a shelf for several years. One leached out the other didn't.
The picture is of a '70s black and gold ECU. Notice the run out goes toward the side of the ECU at the bottom of the picture. This is how it was packed in the box. The other blue and gold ECU shows no sign of leaching at all.............
View attachment 1715070096

View attachment 1715070107

interesting...

 

[MoparMike1974]

The potting material used over the years and different mfg varied. It seems like the original ones are more prone to doing this than aftermarket ones.

 

[RedFish]

Because my brother worked in field failure analysis of a mfgrs electronic products, I know a little more about this than I can repeat. What I can say... On the assembly line the gel coat is dispensed from 2 vessels like a 2 part epoxy. The line workers are supposed to flush the lines and exchange both vessels at the same time. This per the product mfgr's instructions. They don't guarantee every part A and part B to be identical and/or that it will cure properly when cross mixed.
The field failures... Some may find gel melting from overheating with intermittent skip, poor idle/fuel mileage, and eventual total failure to follow. Others may find "evidence" that the part A & B vessels on production line were changed on the fly resulting in inadequate cure/set of the gel in X number of units depending on per unit consumption.

 

[barbee6043]

thanks for the insight RedFish. this 79 Volare of mine runs down the road great, but has a small miss at idle. I have not taken the time to check it out. very original car with OLD vacuum lines ( what? 10 miles of them?) ...... no telling how old this EC might be also.
I have always wondered why I see some "spill their blob" and others don't.

 

[adriver]

Because my brother worked in field failure analysis of a mfgrs electronic products, I know a little more about this than I can repeat. What I can say... On the assembly line the gel coat is dispensed from 2 vessels like a 2 part epoxy. The line workers are supposed to flush the lines and exchange both vessels at the same time. This per the product mfgr's instructions. They don't guarantee every part A and part B to be identical and/or that it will cure properly when cross mixed.
The field failures... Some may find gel melting from overheating with intermittent skip, poor idle/fuel mileage, and eventual total failure to follow. Others may find "evidence" that the part A & B vessels on production line were changed on the fly resulting in inadequate cure/set of the gel in X number of units depending on per part consumption.

So what your saying is production quality control just wasn't that great in 1973 ?
There's a surprise.
Don't buy a car made on a Monday or Friday.

 

[RedFish]

thanks for the insight RedFish. this 79 Volare of mine runs down the road great, but has a small miss at idle. I have not taken the time to check it out. very original car with OLD vacuum lines ( what? 10 miles of them?) ...... no telling how old this EC might be also.
I have always wondered why I see some "spill their blob" and others don't.

Yeah the vacuum system was a nightmare from mid 70s to early 90s. Those lines, ported vacuum switches, etc.., can still be a headache where emissions are tested/regulated. The lucky ones can toss 90% of that crap. Good luck with it.

 

[barbee6043]

Yeah the vacuum system was a nightmare from mid 70s to early 90s. Those lines, ported vacuum switches, etc.., can still be a headache where emissions are tested/regulated. The lucky ones can toss 90% of that crap. Good luck with it.

this is my first F body. pretty much a survivor. I love the simplicity of the early cars, pretty much 70 and before, and actually prefer the early 60's.... so a ' 79 is a STRETCH for me! I hate to start ditching ( un needed to me) emissions stuff, vacuum lines etc since it is so in tack and original. I might just wind up letting letting it have a new home. I have a 62 Lancer and 71 duster I am working on now. yes they run on points! ha
even AC is totally un necessary to me!!! ha

 

[RedFish]

So what your saying is production quality control just wasn't that great in 1973 ?
There's a surprise.
Don't buy a car made on a Monday or Friday.

I learned about gel coat in 1999. I gained answers to questions I had for several years. Now that our replacement parts are built offshore, we can't know what quality we'll get.