: Consequences of driving with failed HG

08-25-11, 08:28 AM
99 Deville - What can be done to the engine that has failed HG and was in camel mode several times? Engine is running a bit rough even when it's not overheating, wondering if it's because coolant is getting into cylinders or there is an internal damage.

08-25-11, 09:04 AM
possible cracked block from Over heating
not sure if the heads them self could also be cracked from the over heating but im pretty darn sure the block could have some major damage due to overheating and running in camel mode

08-25-11, 11:34 AM
Maybe the plugs are bad. The engine was supposedly designed to run that way (camel mode) with no damage.

08-25-11, 01:28 PM
Maybe the plugs are bad. The engine was supposedly designed to run that way (camel mode) with no damage.


08-25-11, 03:40 PM
The plugs may be fouled. As far as I know those are the original 41-950s from '98 (105,000 miles). So there is a chance that there's no damage done except the plugs? Except cracked blocks, I am 95% sure it's still fine.

Back from the trip, I am about to start working on my Deville once the weather gets settled. Too hot to do any work.

08-25-11, 04:31 PM
Maybe the plugs are bad. The engine was supposedly designed to run that way (camel mode) with no damage.

Yeah, but I'm sure the motor wasn't designed for the head bolts to pull out or for any of the blocks to crack.....yet they do.....
I would NEVER intentionally run one in "camel mode".........if I've got cell coverage and a place to park it, I'm stopping it, letting it cool and adding water.

08-25-11, 10:12 PM
So there is a chance that there's no damage done except the plugs?
A good chance.

I would NEVER intentionally run one in "camel mode"
Oh, neither would I (unless I was being shot at), nor would I recommend it. Just saying there "should" be no other damage like cracked block or heads or warped heads.

08-26-11, 09:53 AM
I would imagine a cracked block could happen if cold water is added to a hot engine. Like cracking a hot pot that's immersed in a cold sink. Just a theory. I doubt the overheating in and of itself is the culprit, but im no expert

I suppose the question should be at what point should the engine cool to before adding water?

09-08-11, 02:45 AM
I have driven one of my 1999 Devilles nearly 17,000 miles with blown head gasket. In summer I have to be careful of a few certain roads with steep hills and in winter its just like a normal car. I did have a spark plug crack once in rear of motor as well as trash an 02 sensor. I picked up another car cheap KNOWING it had an issue and do plan to fix it the right way eventually but decided to register and drive it in meantime anyway. So far so good and I have really been pushing my luck with this 138,000 mile motor since I have other blocks if I do destroy it. I DO NOT drive in camel mode. If I screw up and reach it I quickly stop. However, I have learned that turning on heater with high fan helps cool it down quicker. I also added a pressure bleeder intended for hot water boilers on the water pump return line and its slightly open at all times. What this does is allow pressure to bleed off overnight so I can avoid that rough idle when first starting since there is obviously some coolant seeping into cylinder while car is not running but system is pressurized.

Now, I really have been pushing my luck and have been able to get back on the road about 20 minutes after an overheat that makes me have to stop. I have the pressure release lever cap so I can get the cap off quicker. I keep the special hose clamp pliers in car and disconnect upper radiator hose at the engine. I then use the same coolant that boiled out that I capture in an auxillary non-pressurized recovery reservoir. I pour the coolant into the top hose and it fills the radiator and seeps into the engine at the water pump. Either the thermostat is still wide open or it seeps through the holes I drilled in it. On average the engine is around 235 as I am doing this and its hard to even handle the coolant container as I pour it into car. I find that this procedure allows me to drive off and be fine after topping off system in the normal location once I reconnect hose. The "normal" way the cars will just heat right back up immediately after driving off unless I waited at least an hour or longer. Something to do with too much air trapped in system while engine is still hot.

Again, take this with grain of salt as I dont care if I ruin the block and understand I am risking getting burnt. In my mind if I cause damage it would most likely be at the water pump housing or radiator since the coolant is still very hot as I dump it back in.

09-08-11, 10:49 AM
Your engine will be fine. I have personally seen a friend drive 50+ miles in the summer heat in camel mode and no damage was done to the engine. The engine was heat knocking and dieseling so bad that I knew for sure once it cooled it was trash. Sure enough, after it cooled the car cranked and ran but seemed to stumble. I figured the worst and tore it apart expecting carnage but everything was just fine the plugs were just fouled.

They needed the car but didnt have the funds for a new engine so we took a shot in the dark and went ahead and inserted the old engine. That was 6 months and 10,000+ miles ago and the engine still runs like a champ.

Thumper- The cracked blocks on 2000+ northstars are not caused by overheating as far as I know. They are a result of the engine block casting being porous and defective.