I've had my '93 Lightning for about oh what...6 years and 45K miles now. I'm the 4th or 5th owner and it has had a lot of modifications and upgrades along the way. Trans, converter, blower, ported al heads, cam, etc.
Anyway, it never ran smooth above 4500...always had a little shake to it. Engine was rebuilt at 115K, it now has about 160K on it. I figured whomever rebuilt it last time did a crappy balance job.
Well, last week I was racing a new Vette (beat him by the way LOL) and at about 5200rpm in 3rd, the water pump flange decided to kick about 15deg sideways and it felt like the engine lost a rod.
Incidentally, this truck has eaten 3 water pumps and a fan clutch in 45K miles...1 for bearing, one for leaking out the weep hole, and now this one. It's also had a idle heating problem...slowly heats up at idle; always has.
So, I started thinking about this and decided I'd change a few things...
- New Stewart water pump (high quality oem-like hi-flo unit) instead of the kragens cheapie.
- Electric fan swap to Lincoln Mark VIII fan
Finished that Saturday...and what do you know. The engine vibration is gone. Glass smooth to 6200rpm. It appears that the damn fan and/or spacer was causing an imbalance all along and shaking the sh|t out of the last 3 water pumps and took out a fan clutch too
And, the cooling problem is gone...that lincoln fan moves some serious air; and is an easy retrofit. The water pump flows 30% more than stock at idle as well. It's a nice stable 180deg all the time now.
Anyway, just another example how simple crap can cause big headaches, for some reason I'm never able to see the obvious on my own vehicles until I've spent a few hundred bucks and a few dozen hours feeding it parts to eat. LOL.
...such is life.