Engine Shake related to coolant?

[themarquis78]

Hello all. Just got done rebuilding my newly purchased FJ62 and saw there was a minor coolant leak. Seemed to be coming out right at the cap so I ordered a new cap. It wasn't leaking a ton so I didn't worry about driving it.

I drove it about 30 miles from where we were working on it to my house for the first time and could feel a very noticeable shake while at freeway speeds. I had it at a mechanic for something else and had them look into the shake but they said they couldn't reproduce it. When I got the 62 back I couldn't feel the shake either. I played it off as a "newly rebuilt motor nuance."

My radiator cap arrived and so I put it on as well as topped off the coolant. It didn't seem to be leaking so that seems like it cleared up the problem. But...the shake is back. And I realized that both times I noticed the shake where when the coolant had just been topped off. Is that really the cause of it?

Anyone have any ideas as to why I'd be getting this shake? Any insight is greatly appreciated. Thanks

 

[acarnes83]

I don't see how coolant level, either too high, too low, or somewhere in between would cause the motor to shake. If your coolant level is too low you should just have overheating, not shaking. And if it's too high it should just build up pressure and puke out the overflow.

However, if you're convinced they're connected, the semi-scientific way to test your theory would be to drain some coolant, then run the truck. Does it shake?

Replace the coolant and drive the truck. Does it shake?

Do this a few times until you can determine that the two conditions are absolutely connected or that they are not.

 

[themarquis78]

Yeah, that was my thought as well, to carry out that kind of test. They seemed about as related as ice cream and hammers which is why I posed the question. When I get out of work I might try draining some of the coolant to see how it affects the conditions. Mostly, I was looking to see if anyone had had a similar problem.

 

[haryv]

Isolate the shake to the particular cylinder. Then remove the plug to see if it looks new or, steam cleaned. That is the primitive way. The other way, is buy a combustion gas detection kit and use it when then engine is as full operating temperature. If fluid in tester changes color, you have a head gasket leak.

Another way is to goto a shop that has a four gas analyzer and ask the mechanic to put the sniffer tube above the opening of the engine while the engine is running both idle and while tires are spinning "on jacks" and under load use brakes for short periods of time while engine rpms are near highway speeds.

 

[vipergrhd]

shut off

If you could make it shake again why don't you try shutting off your engine to see if it is from your engine or drive train while driving on a straight road.just my 2 pennies.

John