Vibration over 4,000 rpms? (long)

[will it sho?]

Hey all,
I posted a couple of weeks ago describing my problem with an oil leak that I had. I'm a college student at SMU at Dallas, I'm from Virginia and I was planning on taking my 1992 SHO back to SMU. So, I needed to get this leak taking car of as soon as possible. There was always a small oil leak ever since I bought it a year ago with 143,000 miles (151, 000 now) on it. Recently, since I've been off for winter break, the leak got increasingly worse. Believe me, on the verge of taking a 1,300 mile trip, this was not good. A friend of mine recommended a mechanic that was a personal friend and someone you could trust.
Since I've had the car, I've always have taken the car to a Ford dealer, the same place that my dad takes his F-150. They were good and trustworthy, but I figured this job would be pretty expensive at the local Ford dealer, so I thought this mechanic guy would be worth it. I knew it had to be the rear main seal going and that it would require actually taking the transmission apart to get to it. Keep in mind, there was always a time issue involved. Also, Kenny, the mechanic, had done my exhaust over this past Christmas which I was quite impressed with.
Anyway, I dropped it off this past Monday and Kenny went to work. It turns out he found out old problems that I had dismissed as fixed from other Ford dealers. For instance, my lights on my instrument cluster would illuminate and my EATC would shut off occasionally over speeds of 50 mph. Well, it turned out my alternator was overcharging my battery. An average alternator in our cars is supposed to charge about 14 volts. My old one that came with the car was charging 18 volts. Kenny actually showed sulfuric acid creeping out of the battery, not good. So, the alternator had to be replaced as well as a leaking radiator. It had to be done, so I understood that. Even though the original job jumped from $500.00 to 1,000.00, I knew it had to be done for the journey. Honestly, my father and I were glad to know that Kenny could pick out these other problems that would eventually turn out to be problems down the road.
Well, today was our trip day. My father and I picked up the car and took off. Just to recap, a new gasket had been installed, as well as a new alternator (that now charged the right amount of 14 volts) and a new radiator. Anyway, my whole reasoning for this post is what we encountered a few miles down the road. When getting up to speed and pulling 4,000 rpms, I noticed a distinct vibration, almost like a buzzing, from the engine. Make no mistake, there was not a vibration in my clutch, it was definitely from the engine bay. Nevertheless, below 4,000 and above 5,000 rpms there was no distinct vibration. Dad originally thought it was just me, but I make it my business to know the SHO, I definitely knew there was something different. I knew that there was something different. Eventually, Dad noticed it too. Well, what can I say; I’m not really sure what this is? I know that the transmission had to be pulled out to do this job, but I’m not sure exactly what else was taken apart. Could it be the headers that are loose?
While this is the biggest issue bothering me, the oil problem is definitely improving. We did loose about 1 quart of oil in about two days and 1,000 miles of driving (it was about 1 quart for 200 miles before). If you have any ideas about the vibration and a fix for it, please let me know. Please understand that I am a college student and that I am not trying to **** my parents with automotive repairs. Just as a side note, I bought this car and I intend to pay my father back for any repairs. I also understand that I am coming up on my 160K tune up and the age of my engine without this tune up could be a source of oil loss. However, if you have any advice I am all ears. If you’ve made it to this point, thank you for your interest and advice.

Paul

 

[91taurisho]

It is not reasonable for your exhaust manifolds(headers) to be loose as they should not have been touched... The Y-pipe on the other hand is very possible. I have had that vibration on my SHO since I replaced my clutch.(It might have been there before shrug but I had only had the car 4 hours before the tranny and clutch blew up. doh ) I had sheared off a manifold stud and thought the ****** was vibrating with the ghetto rig I had done. Well, I have since replaced both manifold and stud and it's still there. shrug I'm not too worried about it, it's just that the engine is vibrating and it makes something rattle. Every car(even cars with 10 miles) has this, it's just more evident in older cars because things loosen over time. If it bothers the living h*ll out of you then get under there and look at the Y-pipe(where it meets the manifold and the catback system) and wiggle the thing with your hands. If it moves quite a bit then that is your problem... If not then check the heat shields on your exhaust manfilds...

Just a few ideas for you to think about!
Good luck
Scott

 

[SHO_Driver]

Do you get the same vibration in neutral @ 4000? I'm also thinking an exhaust issue.

 

[Rockledge]

Since the secondaries open at just about 4K, maybe that has something to so with it? Or maybe that's when you feel it the most. shrug

And how about those "tranny-to-engine" bolts that I've read about in a few threads ...the ones that people sometimes forget to put back in after servicing the clutch/tranny (I guess they even vibrate loose themselves sometimes and fall out)?

 

[masho95]

Rockledge:
And how about those "tranny-to-engine" bolts that I've read about in a few threads ...the ones that people sometimes forget to put back in after servicing the clutch/tranny (I guess they even vibrate loose themselves sometimes and fall out)?

I think you're talking about the tranny to oil pan bolts. There's two bolts on each side of the oil pan that hold the bottom of the tranny to the oil pan. They can easily be stripped if overtightened. Even if securely tightened I've had one of mine back out to be finger tight. This might cause a vibration if they are loose and the vibrations will travel through the car and you might think it's coming from somewhere else when in fact it's coming from tranny because of the loose bolts. If they are still secure I'd check the condition of all your mounts, including the tranny mount. There's a writeup on www.shotimes.com to tell you how to check for worn mounts. Good luck finding the problem.

 

[will it sho?]

Thank you all for you ideas and advice. I will try to check them out one by one. It does vibrate while it is in neutral at and over 4,000rpms. I think that an exhaust issue would make sense, but I sure hope it isn't the tranny to oilpan bolts. Nevertheless, Kenny did mention that he had to take the transmission from the oil pan to replace the gasket, so this may be a realistic possibility. Anyway, I will keep you all up to speed.

Paul

 

[sdpatt]

If you would drive up Central Expressway a few miles to the Spring Valley exit in Richardson, I would be happy to take a first hand look at your SHO to get a handle on the oil leak source and the vibration. Please see your private message for my contact information.

 

[LI_SHO]

hate to revive a dead thread...but I just installed a reman alternator, and I now get the vibration above 4000rpms as described here. With my old alternator I had no problems, but there seems to be an almost moaning buzz when I go above 4k while driving or even in neutral. Has there been a resolution to this sdpatt?

 

[will it sho?]

Hey,
When I went to sdpatt, we were under the car changing some O2 sensors and a heat shield that was well rusted fell off. Ever since then, I don't have that vibration problem anymore. Sorry this does not help your problem, but I didn't want to leave you hanging. Is everything tightened correctly on the alternator? I am curious to see what others say.

Best,
Paul Bennett