Author Topic: How Bad is it ??? (Read 3854 times)

Justonegear · « **on:** December 21, 2009, 11:47:14 AM »

Have a 91 318is with about 98K on it. Due to my own error the engine overheated. I caught it as the needle was just going into the bottom of the Red Zone and pulled over. I nursed it home although the temp brushed the Red Zone several more times between rest stops. It was never pegged and I was actually able to drop the temp well below the Red Zone while coasting as it was a fairly cold night, at least by Las Vegas standards. I'm not very familiar with the M42 engine. I have not gone through the normal post overheat drills yet, ie compression, leak down. Crystal Ball question I know, do you think that I did any damage to the engine. It never acted funny during this time. However prior to it I was chasing a missing/ rough, poor accellaration problem which seems to be getting worse even after a new set of plugs. The engine starts, idles, and runs fine at high RPM but seems to bog in every gear at lower to mid RPS. Thanks for any help. Happy Motoring

Justonegear · « **Reply #1 on:** December 22, 2009, 03:57:54 PM »

Well Compression test now complete. #1-185 #2-187 #3-190 #4-185 lbs, guess that's about normal.

DesktopDave · « **Reply #2 on:** December 22, 2009, 04:05:48 PM »

Seems OK to me. I'd check the aux fan resistor. Sounds like it might be a water pump though.

quinn11m20 · « **Reply #3 on:** December 22, 2009, 04:46:37 PM »

Some years ago I was doing 95 up I-95 and my baby overheated. I turned off the engine and coasted for about 2 miles into a Chevron station. Luckily for me they sold coolant. Well when letting her cool down, I poured coolant into her and fixed what went wrong. The upper hose split with the plastic inlet, exploded right off. After getting her home, I had to purchase a new radiator. With that, I replaced all the hoses and the thermostat. Including the water pump.
I truly believe it was a combination of things, my speed and the oil I use. Since I was doing 95 when I shut off the engine, she got air cooled. The oil, well its 20W50 and its Castrol High Mileage. I wrote a letter to them telling my story. I then recieved some gift certificates and $100 gift certificate to Advance Auto Parts. But I digress....

As for the compression I would recheck it. I have 252k and mine ( about 3 months ago ) are all above 205. As long as one cylinder is within 50% of the others, I believe, your ok. Someone correct me if I am wrong. These engines with the propper care will outlast a lot of others on the road. Have some faith and it will take you everywhere. Believe me.

For the compression I think minimal was 190 PSI after that your looking into a rebuild at least. You know you have to remove the throttle body to get a propper compression test, right?
Also, since it has been posted on this site so many times, research for the "under the intake mess" and make sure all your hoses are in good standing. Any visible cracks and you might want to change them.

I think this is the most I have written on a thread. Well, good luck.

dwtaylorpdx · « **Reply #4 on:** December 22, 2009, 11:01:08 PM »

Compression test if half of it, now do a leak-down. It tells the real story...

Dave

Justonegear · « **Reply #5 on:** December 22, 2009, 11:54:02 PM »

I didn't remove the throttle body, was I suppose to ? Also, chasing the poor running condition. It runs fine cold it's after it comes up to temp it starts to stumble when you gas it. At low RPM's its all good. When you punch it, it acts like it's almost flooding out and the car seems to vibrate a bit

? The stop test show a 1223 code

thanks

dwtaylorpdx · « **Reply #6 on:** December 23, 2009, 01:08:43 AM »

The TB will affect the result slightly. For your purposes the compression showed no catastrophic damage. Now you need to check out whether you have lighter damage, warped head, valves, cooked pistons etc. < hint LEAKDOWN TEST > LOL

You need to make sure the integrity of all the vacuum lines is good.

You need to test or replace the O2 sensor.

Nearly every intake and ignition issue will trigger the O2 failure code. so its best to learn how to test one, its a google away...

Dave

Justonegear · « **Reply #7 on:** December 23, 2009, 10:20:42 PM »

Thank You for the help, jump back into it in a few days. Happy Holidays

Chalino · « **Reply #8 on:** January 06, 2010, 02:53:10 PM »

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