Acid covered PCM
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Pro
Joined: Aug 2008
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From: Colorado springs
Acid covered PCM
I've been knee deep in a project with my C5. When I popped my fender off and saw my PCM, 
Rust and battery acid had been eating at my frame and covered my PCM.
I urge you guys to pop your inspection panels off in the fender wells, and look for this. Mine was at a point that it had already moved to the bottom of the frame and started eating there too.
I was able to knock the scale off, but I'm worried about the inside of the frame. I'll be painting it over, I thought that everybody should know because it seems like something that could happen to anyone.
Rust and battery acid had been eating at my frame and covered my PCM. I urge you guys to pop your inspection panels off in the fender wells, and look for this. Mine was at a point that it had already moved to the bottom of the frame and started eating there too.
I was able to knock the scale off, but I'm worried about the inside of the frame. I'll be painting it over, I thought that everybody should know because it seems like something that could happen to anyone.
Drifting
Joined: Feb 2003
Posts: 1,761
Likes: 235
From: North Carolina
Leaking side post ACDelco batterieis were a big issue with the early C5 years until owners replaced the original battery. Forgot what year they finally went with the top post Delco's from the factory, might have been around 2002-2003 model year.
As the early C5's change hands more new owners will come across this unpleasant surprise.
Good luck with your repairs, there are several threads over the years that detail repairing this damage.
As the early C5's change hands more new owners will come across this unpleasant surprise.
Good luck with your repairs, there are several threads over the years that detail repairing this damage.
Last edited by MAC5; May 22, 2012 at 07:23 AM.
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From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
Sad to hear this sorry story still going on. Make sure you treat the acid with baking soda to neutralize it before you repaint.
Leaking batteries was a big issue from 97 to 00. There was a design fault with the side posts which caused the case to crack if they were over tightened. The OEM AC Delco batteries with the problems were replaced by AC Delco AGM batteries.
97-00: 78-7YR "Leakers"
01-03: 75P-7YR AGM battery
04: 86-7YR Top-post battery
Side post damage
PCM damage
The reason many of us invested in Optima Red Top AGMs is because of those scares and the fact that AGMs are unlikely to leak. I had a leaking AC Delco on a Camaro and a dead AC Delco AGM on my Vette. Unfortunately, the downside of AGMs is that they don't take kindly to being discharged. With the 20MA drain on our cars, leaving the car idle for any length of time can kill the battery.
Here are some of the early threads if you are into horror stories:
http://forums.corvetteforum.com/c5-t...-pictures.html
http://forums.corvetteforum.com/c5-g...kage-pics.html
Leaking batteries was a big issue from 97 to 00. There was a design fault with the side posts which caused the case to crack if they were over tightened. The OEM AC Delco batteries with the problems were replaced by AC Delco AGM batteries.
97-00: 78-7YR "Leakers"
01-03: 75P-7YR AGM battery
04: 86-7YR Top-post battery
Side post damage
PCM damage
The reason many of us invested in Optima Red Top AGMs is because of those scares and the fact that AGMs are unlikely to leak. I had a leaking AC Delco on a Camaro and a dead AC Delco AGM on my Vette. Unfortunately, the downside of AGMs is that they don't take kindly to being discharged. With the 20MA drain on our cars, leaving the car idle for any length of time can kill the battery.
Here are some of the early threads if you are into horror stories:
http://forums.corvetteforum.com/c5-t...-pictures.html
http://forums.corvetteforum.com/c5-g...kage-pics.html
Last edited by DeeGee; May 22, 2012 at 08:33 AM.
Thread Starter
Pro
Joined: Aug 2008
Posts: 574
Likes: 5
From: Colorado springs
Sad to hear this sorry story still going on. Make sure you treat the acid with baking soda to neutralize it before you repaint.
Leaking batteries was a big issue from 97 to 00. There was a design fault with the side posts which caused the case to crack if they were over tightened. The OEM AC Delco batteries with the problems were replaced by AC Delco AGM batteries.
97-00: 78-7YR "Leakers"
01-03: 75P-7YR AGM battery
04: 86-7YR Top-post battery
Side post damage
PCM damage
The reason many of us invested in Optima Red Top AGMs is because of those scares and the fact that AGMs are unlikely to leak. I had a leaking AC Delco on a Camaro and a dead AC Delco AGM on my Vette. Unfortunately, the downside of AGMs is that they don't take kindly to being discharged. With the 20MA drain on our cars, leaving the car idle for any length of time can kill the battery.
Here are some of the early threads if you are into horror stories:
http://forums.corvetteforum.com/c5-t...-pictures.html
http://forums.corvetteforum.com/c5-g...kage-pics.html
Leaking batteries was a big issue from 97 to 00. There was a design fault with the side posts which caused the case to crack if they were over tightened. The OEM AC Delco batteries with the problems were replaced by AC Delco AGM batteries.
97-00: 78-7YR "Leakers"
01-03: 75P-7YR AGM battery
04: 86-7YR Top-post battery
Side post damage
PCM damage
The reason many of us invested in Optima Red Top AGMs is because of those scares and the fact that AGMs are unlikely to leak. I had a leaking AC Delco on a Camaro and a dead AC Delco AGM on my Vette. Unfortunately, the downside of AGMs is that they don't take kindly to being discharged. With the 20MA drain on our cars, leaving the car idle for any length of time can kill the battery.
Here are some of the early threads if you are into horror stories:
http://forums.corvetteforum.com/c5-t...-pictures.html
http://forums.corvetteforum.com/c5-g...kage-pics.html
I know there is issues with space, but computer under a battery...just seems like an afterthought idea.
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A good reminder - why GM put a computer under the battery is a mystery to me - the potential for disaster should have been apparent.
Good luck with the acid repair - hope everything comes out OK.
Good luck with the acid repair - hope everything comes out OK.
Drifting
Joined: Feb 2003
Posts: 1,761
Likes: 235
From: North Carolina
Luckily I caught mine before it started to eat into the PCM casing, That much damage would make me cry! The thing that gets me, is if you look into the battery tray, you hardly notice anything. I know there is issues with space, but computer under a battery...just seems like an afterthought idea.
I know there is issues with space, but computer under a battery...just seems like an afterthought idea.
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Start looking for a replacement PCM now...I will post my situation soon...car has been in the shop for a month...we could not locate the part either from GM or aftermarket or rebuilt...another 'can't find' part to add to the list....
Melting Slicks
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St. Jude Donor '13
Even modern aftermarket batteries are still prone to leaking. My shock and horror led me to optima. Then after abusing the first one that led me to a float charger. Just another **** poor design flaw by gm to put an aluminum cased computer under the battery.
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From: Horncastle Lincolnshire, England
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It's been funny watching the "My Optima died" threads here over the years. At least Optima owners just pulled the battery and put in a new replacement. Memories are short on how bad it was in the early days.
I still think the leaking batteries was the biggest scandal in the C5's history.
I still think the leaking batteries was the biggest scandal in the C5's history.
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From: Lake Mary Florida
It doesn't have to be that severe to cause a problem. Here's a fairly new battery that started seeping from the top. I caught it when removing the battery system for replacement of the AC accumulator.
The green stuff is corrosion going on from the acid drips.
How often does one consider a major maintenance (AC compressor/accumulator replacement) a blessing in disguise, this one was. I would have never known or seen that little trickle down the side the way it sits in the compartment.
So, yes I agree, pull your battery and examine it and remove the four bolts holding the tray in place and examine that computer.
The green stuff is corrosion going on from the acid drips.
How often does one consider a major maintenance (AC compressor/accumulator replacement) a blessing in disguise, this one was. I would have never known or seen that little trickle down the side the way it sits in the compartment.
So, yes I agree, pull your battery and examine it and remove the four bolts holding the tray in place and examine that computer.
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It's a bit fiddly to install, but .....
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Oldtimer
Sad situation, The main reason . . .
Sad to hear this sorry story still going on. Make sure you treat the acid with baking soda to neutralize it before you repaint.
Leaking batteries was a big issue from 97 to 00. There was a design fault with the side posts which caused the case to crack if they were over tightened. The OEM AC Delco batteries with the problems were replaced by AC Delco AGM batteries.
97-00: 78-7YR "Leakers"
01-03: 75P-7YR AGM battery
04: 86-7YR Top-post battery
Side post damage
PCM damage
The reason many of us invested in Optima Red Top AGMs is because of those scares and the fact that AGMs are unlikely to leak. I had a leaking AC Delco on a Camaro and a dead AC Delco AGM on my Vette. Unfortunately, the downside of AGMs is that they don't take kindly to being discharged. With the 20MA drain on our cars, leaving the car idle for any length of time can kill the battery.
Here are some of the early threads if you are into horror stories:
http://forums.corvetteforum.com/c5-t...-pictures.html
http://forums.corvetteforum.com/c5-g...kage-pics.html
Leaking batteries was a big issue from 97 to 00. There was a design fault with the side posts which caused the case to crack if they were over tightened. The OEM AC Delco batteries with the problems were replaced by AC Delco AGM batteries.
97-00: 78-7YR "Leakers"
01-03: 75P-7YR AGM battery
04: 86-7YR Top-post battery
Side post damage
PCM damage
The reason many of us invested in Optima Red Top AGMs is because of those scares and the fact that AGMs are unlikely to leak. I had a leaking AC Delco on a Camaro and a dead AC Delco AGM on my Vette. Unfortunately, the downside of AGMs is that they don't take kindly to being discharged. With the 20MA drain on our cars, leaving the car idle for any length of time can kill the battery.
Here are some of the early threads if you are into horror stories:
http://forums.corvetteforum.com/c5-t...-pictures.html
http://forums.corvetteforum.com/c5-g...kage-pics.html
C5's and this is the flaw that is most disturbing. And in both cases how in the hell do you weld anything there without setting the car on fire?
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