Should I worry?

[OniZ]

So yesterday I was helping a friend with his car and we came to the point where we had to go to the store for something. So I drove my Z about half way there we ran over a belt, (and I just randomly thought to myself I would if that was mine) after that I noticed the temp gauge was pegged all the way at 250. I tapped the gauge to see if maybe it had broken or the connection had become loose but it stayed there. Turns out that my belt (my only belt) either broke or fell off, so my alt, crank, and water pump weren't getting any rotations. My concern is could this have done some serious damage to the motor? I didn't stop immediately. Any recommendations on this would be helpful.

[SteveJ]

There isn't much you can do unless you are ready to tear the engine apart. Check the compression. Keep an eye on the oil and radiator fluid to see if one is getting into the other. As long as all those are okay, you probably don't have much to worry about.

[tlorber]

Check the the oil for water and smell it. Check the water for oil, and then put a new belt on. The major concern would be the fact that the water pump wasn't pumping and the head warped. If the fluids look, run the car and see if vapor comes out the pipe (after the car has warmed up) and keep an eye on both the temp and the coolant level.

How long were you running it without the belt?

Coincidentally, I was down your way yesterday (Garden Grove and Westminster) buying a Z.

Edited May 15, 2011 by tlorber

[d240zx2]

During the SCCA SW Division Solo II run-offs in 1972, final run of the day, I lost my belt. I don't know when during the run this happened. I crossed the finish line with the temp gauge off the scale @ 6000 rpm. Got a new belt, put it on, and drove it the 1300 miles from Penwell, Texas to Montgomery, Alabama with zero problems. Since then, I've had the head off and skimmed... no significant deviation from plane flat. Those L24 engines are tough rascals.

[JLPurcell]

During the SCCA SW Division Solo II run-offs in 1972, final run of the day, I lost my belt. I don't know when during the run this happened. I crossed the finish line with the temp gauge off the scale @ 6000 rpm. Got a new belt, put it on, and drove it the 1300 miles from Penwell, Texas to Montgomery, Alabama with zero problems. Since then, I've had the head off and skimmed... no significant deviation from plane flat. Those L24 engines are tough rascals.

Ditto

As you have already been advised, the worst case at this point is a warped head. If that is the case your temps will not stay down, your oil will become milky (water) and possibly oil in your cooling system. That would require milling your head and installing a new head gasket. jlp

[Diseazd]

And remember.....never add fresh water to a overheated engine, the drastic change in cooling will really warp an engine, and when you add water to a warm engine, start it before adding water or coolant. I warped the valves on a 52 Jeep adding cold water to a hot engine and it was running when I added it!

[OniZ]

I just checked the fluids right now coolant seems to be fine and so does the oil but I haven't turned over the motor just yet. As for how far I drove maybe a block in a half it came off at euclid and I stopped at brookhurst and stanford which isn't to far away. I have an old belt I can put on to test but I will go buy a new one later this afternoon.

[5thhorsemann]

No worries, that motor ain't made of wax, it can take alot more abuse than that.

[OniZ]

Ok coolant is fine even after the thermostat opens, and the oil is ok also. Noticed the valve cover bolts were loose so I tightened those back down. I do get some vapor/smoke from the breather on top but nothing more that what it was before the belt snapped. One other random thing I change the thermostat a few months ago when I did the coolant system and once I put it in the gauge sat a lot higher is that normal? I know with the different thermostats it supposed to open at a different temp, but does it sit at a different point too? For reference the old one sat at 1/2 the new one sits a little under 3/4.

[AZ-240z]

Do a quick search for stock vs. aftermarket thermostats. ONLY USE NISSAN OEM THERMOSTATS!!!!!!!

Dan

[OniZ]

I've had no luck on the thermostat stock vs aftermarket but have found some other things I didn't know,

[tlorber]

I didn't realize you only ran it a couple of blocks. You'll be fine. When I did this to my car last month

I severed the radiator. I had to drive it like this for about 25 miles on a dry motor to get it back to the hotel. Luckily it was cool out and I kept shutting the car off at the top of each grade, but I made it back and was able to put in a temporary radiator and drove the car 225 miles home. No issues on the drive other than some puzzled looks from other drivers.