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1.9 GT overheated, now it knocks...

2660 Views 5 Replies 3 Participants Last post by  greensmurf20
1.9 GT overheat

been workin on a 70 GT. took it out tonight and when my dad came back with it.(i'm only 14) it was pegged out on the temp gage. now when the car first fires up it knocks really bad and then goes away. what could this be? serous, minor? any help would be greatly appreciated. thanks
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Check the timeing- bad timeing will make the engine overheat real fast. Also would explain the knocking. Good luck
the timing is right and all. the car overheated because one of the heater hoses somehow got cut! it happened last night and today it knocked the first time i started it up and then after that it never did it again.....hmm. replaced the hose and fixed a oil leak and little things like that today and just took it out an hour ago..... the first time the car has been on the road in a couple years, and kept running better and better as we went. drove it for about a half hour and shut it off at the house and started it again and still didnt know like it did this morning and last night. maybe it was just one of those never to be found out things i guess. THANKS FOR THE HELP BARONBORS!!!!!:)
A "knock" after overheating can be a VERY bad thing. Did it "knock", or "tap"? A knock, which I would describe as a louder, deeper sound, might indicate a spun bearing, a broken rod, or worse. This is a BAD thing. But it won't go away (usually), so hopefully that is not what you have.

Another source of a knock is a loose piston or worn cylinder. This is usually a softer, quieter knock, and sometimes goes away after the engine warms up and the piston expands. Chrysler V-6 engines (such as the 3.3 and 3.8 litre in the MiniVans) are notorious for this, and Chrysler can be convinced to rebuild an engine if is in the warranty period. Ask me how I know this. But I digress...

A "tap", such as a loose or pumped-off lifter makes, might be what you heard. It often occurs at an idle, when the oil pressure is low, or when the oil level is low. Some folks I know (Kat must have burning ears about now!) use this method to determine when to add oil. Bad idea!

Overheating can also cause a cracked head, which might cause a leak in the oil galley, and the resultant low oil pressure can cause a lifter to tap. And a crack is usualy fatal, since it often also causes the coolant and oil to mix (another BAD thing), not to mention loss of compression and acne. Wait, I was just testing to see if anyone was still paying attention....

How is your oil pressure? Is your oil colour OK, or is it getting greyish (caused by contamination with coolant)?

Tell us how you make out.
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I know what you mean by running better and better as you drive it. My Desert Rose was an East California car that hadn't run in 6 years. Had it transported to Texas and spend a year getting it ready for the road. After inspection and driving it around for awhile, top speed was 50-60 mph and the engine sounded like I was going to throw a piston through the side of the block. Now after 8 months on the road and some tweaking, top speed 95-100 MPH and runs much quieter.
well two days now and it hasnt knocked on start up anymore. idk what it was or why it did it but just glad it stopped. if anything i think it mighta helped the motor for some reason. it carrres twice the oil pressure at an idle and seemed to idle better. we took it out last night again and drove 11 mile problem free(except for that skunk we hit and the shift boot is a little torn so dang did the smell get in fast!!!!) had to clean them fur chunks off this morning with a pressure washer. changed a leaky wheel cylander and bled brakes. took it out again today and the hunk of S*** Solex did something and was flooding the car out really bad. tore that apart and cleaned it all out. i'm stayin home tomarrow cuz its my birthday and i'll put it back and fix some little things and see what happens. i plan on eventually getting a webber anyway.
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