Start motor w/out coolant?

No one can say 'for sure', but if it was mine I likely would go for it.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

aGraham wrote:

If the engine is cold to begin with you can drive it for a few minutes without trouble.

-Brian

Just watch the temperature (probably won't budge within 30 yards though).

-- JimG

80' CJ-7 258 CID 35" BFG MT on 15x10 Centerlines D44 Rear, Dana 30 Front. SOA 4.56 Gears, LockRight F&R Dana 300 w/4:1 & Currie twin sticks Warn X8000i w/ dual batteries

Your water pump should at all possible should not be run dry because the coolant lubricates the seals but what do I know.

Absolutely. Make sure you have everything secured away from the moving parts.

I personally would not run an engine without coolant for more than 30 seconds.

Tom

NO WAY should you drive it for a few minutes. The cylinder walls will turn red hot and the engine will seize and be destroyed.

30 seconds MAXIMUM without coolant for my vehicles.

Tom

If there is no coolant, the temperature gauge will not work properly. Watching the temp gauge with no coolant is useless.

Tom

Take out all the rad bolts except for 2 of them drive it outside then finish removing it, I changed a rad on my 93 YJ outside 2 years ago in

-15 Deg C weather and it > I am going to be pulling my radiator tomorrow to take it to get fixed.

I am guessing that pushing it or winching it out is out of the question? My

14 year old son gets a kick out of pushing mine out of the garage (the grading works for that stunt...).

You think.?... you don't think the block won't heat the sensor up? Try it... see if you can hold on to the sensor.

JimG

Absolutely no problem. Done it for years on all kinds of cars. If it's an automatic trans don't forget to plug the trans cooler lines or you'll pump all of your trans fluid on the ground in pretty short order. A few comments after reading the other replies.. 1. 30 seconds won't even start to get things warm. There's no coolant in the exhaust manifolds at all and after 30 seconds you can still grab and hold them in your bare hands. The exhaust manifolds are the hottest spot in the engine. The cylinders are cooled somewhat by the incoming air charge. I would suggest that it would take at least 10 minutes for it even to get to operating temp.

Not everybody dies from running with scissors. Unless all your vehicles are supercharged nitro-burning funny cars you're pretty safe running them longer than 30 seconds. When your engine is cold, remove the rad cap and see how long it takes for your thermostat to open. That will give you an indication of how long it takes for your engine to detect warmth.

By the way, the "removal of this tag is punishable by law" thing on sofa cushions and mattresses can be removed after you purchase them.

-Brian

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Hi Brian:

When you remove the radiator cap to see how long it takes the engine to warm up, the engine block is filled with coolant. The original question was about an engine with NO coolant (radiator was removed.) An engine with no coolant will overheat VERY QUICKLY.

I don't know how long exactly, but I'm pretty sure running it for a "few minutes" with no coolant might destroy the engine. For my vehicle, I would run it for no more than 30 seconds or so.

Tom

As I pointed out in an earlier post, draining the rad does not drain the block. The level of coolant in the block is at least up near the top of the cyl walls. But even a dry engine will not overheat, or even come close to reaching operating temp in 30 seconds, a minute, 2 minutes. Take an oxy acetalene torch and hold it against a piece of cast iron and see how long it takes to get red not. Put your hand on the exhaust manifold and run it for

30 seconds. The manifold is not cooled and is the hotest spot in the engine. You can still hold your hand on it after a minute or more. The fresh air charge coming into the cyls is cooling it. The oil in the crankcase is carrying away heat. If there's an engine oil cooler you can even go longer. Think about air cooled engines. 30 seconds won't even get the heat to the fins. But nevermind the theoretical explanations, I've done it a thousand times as a professional mechanic since the early 70's can assure you that there is no risk of damage. You can safely run it until the temp gauge or indicater light indicates a problem, probably a good 10 minutes or more. In fact here in the frozen north if the engine is idling it will run indefinately and not hit operating temp and open the thermostat when the system is full of coolant. You have to have a load on the engine to get it to warm to op temp. Without coolant the temp sender won't be as accurate, but close enough and remember, it's designed to warn well before damage occurs.

Of course you'll do as you like with your vehicle, but everyone should know that if you drop a frost plug and loose all of your coolant in the middle of the road somewhere and have to make an assessment of how much of a hazard you are on the road in the spot you're sitting versus your risk of damage to your vehicle that you have plenty of time to drive to a better spot. I'm constantly amazed and annoyed by where people will leave there vehicles under those conditions, even if they're not endangering traffic they're causing traffic to backup for miles because they believe they'll ruin their engine if they drive the 5 minutes to get it off the road.

Why not remove the coil wire and run it on the starter motor that far? Or get a couple of budies and push it? 30 yards is not very far.

Or even tow the thing on the end of a rope ?

Dave Milne, Scotland

Hmmmm, although running it for a minute to move it 30 yards probably isn't a problem, if it bugs you that much just push it, or tow with another vehicle...you DO have a tow strap, don't you??

Well I went to work on the Jeep and found that I had not lost any coolant this time when I drove it the other day. I did tighten the upper hose, so maybe the hose was leaking and running down. I am going to try driving it to work again and see how it does.

The reason I asked was because I probably would have been doing the work by myself, so towing or pushing the Jeep would probably been out of the question.