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Melted Motor Mount???

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Old Apr 20, 2010 | 07:06 PM
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Default Melted Motor Mount???

I jacked up my car to change oil and noticed some red stuff on my k-member and then I discovered this...



Anybody ever had a poly motor mount do that?
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Old Apr 20, 2010 | 07:15 PM
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Can't say that I have...

Is that the firehawk?
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Old Apr 20, 2010 | 07:21 PM
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Yeah it is.
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Old Apr 20, 2010 | 07:36 PM
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Ok I got over my initial shock and went back out and looked and it's just the back side that melted the front looks fine. They are Prothane mounts and they've been in for less than a year, and they are not close to my headers at all and my car has probably 2,000 miles on my rebuilt motor, hasn't overheated or anything like that.
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Old Apr 20, 2010 | 08:03 PM
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There is another thread about this on here as well. Looks like some hardcore investigation needs to be done on these mounts. Appears there is a bad batch
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Old Apr 20, 2010 | 08:34 PM
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looks like they were made out of bubble gum!! crazy!
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Old Apr 20, 2010 | 08:36 PM
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I contacted Speed Engineering who i bought them from and they said they haven't had a problem with them. He said my header pipe might be too close, but I went and checked and I have over 1 1/2" gap, doesn't sound like that should've melted it. But anyhow he told me to contact Prothane, so I will.
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Old Apr 20, 2010 | 11:06 PM
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Wow, that's nuts... Let us know what they say.
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Old Apr 20, 2010 | 11:17 PM
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that would have to be pretty freakin hot to melt them bad boys.......dont think a lousy header would do that
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Old Apr 20, 2010 | 11:25 PM
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wtf, i'd be pissed
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Old Apr 21, 2010 | 01:00 AM
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The melting point for urethane is around 536 degrees (thanks Marc 85Z28) , so yeah it got hot.....really hot.

Last edited by 7th Darkness; Apr 21, 2010 at 08:51 AM.
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Old Apr 21, 2010 | 01:38 AM
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I have a set of Prothane Poly's on my car and so does my buddy's 98 Z28 and my Bro's 02 SS. All were installed just about a year ago.

I'll have to jack mine up and see if there's any "chewing gum" stuck anywhere.
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Old Apr 21, 2010 | 07:38 AM
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Originally Posted by 7th Darkness
The melting point for urethane is 113 degrees or something, so yeah it got hot.
Perhaps you missed the poly- part? As in POLYurethane? That melts at over 500F. Why would someone use a urethane engine mount!?
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Old Apr 21, 2010 | 08:52 AM
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Originally Posted by Marc 85Z28
Perhaps you missed the poly- part? As in POLYurethane? That melts at over 500F. Why would someone use a urethane engine mount!?
LOL, yeah sure did, it was early what can I say. Fixed post, but looks like they may have forgot the poly part themselves.
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Old Apr 21, 2010 | 03:54 PM
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Ok I called Prothane today and they said that they didn't have a bad batch that he knows of and that their parts are designed as a stock replacement. Which is kinda dumb thing to say cuz if my car was completely stock why would I want polys. But anyhow my headers are stainless and I realize they transfer more heat and my compression is raised slightly and that will increase heat, but I know I'm on the rich side so that has a cooling effect. Also asking around I found out that a stainless header pipe on a dirt bike(which is about the same compression) can easily reach 600 degrees in the first bend. So thinking about that the first bend should be the hottest which is where my plug wires are located and they aren't melting and I bet they're closer than my mount is. I didn't figure they would warranty the problem, I'm not worried about the 30 bucks for another one either, but maybe poly isn't the best material for a mount, maybe msd should make us a mount.
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Old Apr 21, 2010 | 04:01 PM
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If they are stock replacement then why hasnt rubber melted?
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Old Apr 21, 2010 | 05:27 PM
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Originally Posted by Cowboy97
Ok I called Prothane today and they said that they didn't have a bad batch that he knows of and that their parts are designed as a stock replacement. Which is kinda dumb thing to say cuz if my car was completely stock why would I want polys. But anyhow my headers are stainless and I realize they transfer more heat and my compression is raised slightly and that will increase heat, but I know I'm on the rich side so that has a cooling effect. Also asking around I found out that a stainless header pipe on a dirt bike(which is about the same compression) can easily reach 600 degrees in the first bend. So thinking about that the first bend should be the hottest which is where my plug wires are located and they aren't melting and I bet they're closer than my mount is. I didn't figure they would warranty the problem, I'm not worried about the 30 bucks for another one either, but maybe poly isn't the best material for a mount, maybe msd should make us a mount.
There is nothing wrong with polyurethane being used for mounts. It's used by OEMs and aftermarket manufacturers alike. I've got Prothane mounts in mine, and they've been fine for years. I've got ES mounts in my Z28 with uncoated headers, and they've been there over a decade. That is a manufacturing defect. Doesn't mean there was a bad batch, just maybe that one didn't get the right polymer mix or it wasn't cured properly.
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Old Apr 21, 2010 | 07:45 PM
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What brand poly motor mount is that, OP? I want to make sure never to buy it. lol
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Old Apr 21, 2010 | 07:57 PM
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It's Prothane brand, which is the only one I know of made specifically for our cars. If their is another brand someone chime in.
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Old Apr 21, 2010 | 11:39 PM
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You know talking with my dad today he said why don't you just go solid mounts. Why didn't I think of that, lol, after a little research I think I'm gonna alleviate the chance for a melting problem altogether and put solid mounts.
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