# 1985 nissan 720 pickup- the whole thing shakes!



## greasy (Nov 3, 2010)

so I was putting along when the whole truck started shaking and running really rough. it has oil, water, etc. all the basics.

I was able to drive it home but only slowly. if I give it too much throttle it gets really bad. at idle it's almost usable. but it got a little worse by the time I got home. basically it felt like the engine was throwing the truck around a bit.

a friend said he thought it might be the catalytic converter. anyone had anything like this happen? does this diagnosis sound right? 

is the cat converter a permanent part of the exhaust? if I get a new one do I need to weld it in? I'm somewhat handy, more with motorcycles, but I would prefer to do the repair myself if possible...

thanks!


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## playtimeover (Nov 4, 2010)

Hi greasy. That scene also happened to me before. But the difference it didn't thrown my truck around a bit.


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## smj999smj (Jan 1, 2006)

I think you need to back up a step before replacing the converter. a lot of things can cause the symptoms you describe. If you have the 8-spark plug engine, which I'm pretty sure you do, the first thing I would check is the distributor cap and rotor. Check for a whole burnt through the rotor causing ignition crossfire between the intake and exhaust side ignition systems. A bad ignition coil can do the same thing. So can a blown head gasket; it's not uncommon to have the gasket blow between two cylinders on these engines. A leaking intake gasket, also not uncommon on these engines, is another possibility. Could also be a carb issue. You need to diagnose and isolate the problem before replacing anything, otherwise you'll likely spend a lot of money replacing parts that are perfectly fine.


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## greasy (Nov 3, 2010)

smj999smj said:


> I think you need to back up a step before replacing the converter. a lot of things can cause the symptoms you describe. If you have the 8-spark plug engine, which I'm pretty sure you do, the first thing I would check is the distributor cap and rotor. Check for a whole burnt through the rotor causing ignition crossfire between the intake and exhaust side ignition systems. A bad ignition coil can do the same thing. So can a blown head gasket; it's not uncommon to have the gasket blow between two cylinders on these engines. A leaking intake gasket, also not uncommon on these engines, is another possibility. Could also be a carb issue. You need to diagnose and isolate the problem before replacing anything, otherwise you'll likely spend a lot of money replacing parts that are perfectly fine.


ok, I was hoping it would be something obvious, or a common issue. not that lucky...

I'll check the things on your list and see what I find. thanks for the detailed, concise response. I appreciate it.


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## SPEEDO (Jun 9, 2003)

just for grins.... have you checked the engine/trans mounts? carrier brg? u-joints?


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## greasy (Nov 3, 2010)

I'll add those to the list. prob is I'm super busy with school and work and can't find the time for any of it.

thanks.


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## stenbots (Mar 21, 2008)

hi i'd blame the smog stuff idle air solenoid thing remove as much as possible hoses etc and just keep the egr and the vac to the dist simplify dude


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