why are my compression numbers low?

[michael93LE]

I have a 1993 Toyota Corolla LE with the 1.8 7AFE engine in it. 173xxx on the engine, and the other day my g/f was heading out of town and called me from the side of the highway. I headed out there, and asked her was had happened, and she said she was driving, then the car started loosing power and smoking, and she popped the hood and saw the radiator cap had blown off, and there was nothing in the radiator. Sheslowly seemed to lose power going up the hill, im guessing b/c there was so much sludge on the plugs, they were covered with sludge and water. I got the truck and trailer and towed it home and put it in the shop. I pulled the head off and the cylinders were full of water, and when I drained the oil there was about 4 quarts more then there should have been (water was added). I got it all cleaned out, and milled the head and replaced all the gaskets, and still no start. I ran a compression check, and am getting in this order from left to right (70,50,40,70) these number seen really low, especially the #2 and #3 pistons. I squirted a little oil in the top of the cylinders and put the plugs back and just to give it a shot, and it tried to fire but just wouldn't.

can anyone think of any reason why these numbers would be the way they are other then the rings are shot from her driving it on water . I know it is in time, I litterly checked this 5 times, and even flipped it 180 degrees just to make sure that wasn't the issue. It is getting gas, it is getting spark, and it is getting air..... it should run! lol. I leave in a week for my new job until august and really need to get this fixed for her so shes not walking!

[NWMO 95 Prizm Lsi]

Michael,

As I understand it, compression is a nessicity as well. I know with old Ford tractors, they get tired and run down to 90 psi - 110 psi, but below that you can't keep them running.

If you've had the head gone through and you are confident the valves are sealing, that leaves the rings. At 173,xxx miles you mine as well drop a used motor in or go clear through it. Not easy to do in a week either way.

Chris

[michael93LE]

thanks, ya I could do it in 2 days, however its not really worth it. I did not know what the stock psi should be really on these cars, I have always ran higher comp. motors, but thanks. the car isn't really worth a new motor, might just see about parting it out, and scrapping the rest.

[yoshiki2]

Go to a junkyard and look for an engine with low milled. From a Corolla prizm or Celica. 1.6 or 1.8 will work. Check the oil cap and radiator cap no water on oil cap, and noyhing wierd on radiator capp. Also the exhaust just be clean. Once u find an engine with those characteristics take out the oil pan and check the bearings. If they are in God shape that engine may last at least 100k killed. If u bring a friend with u, you could even make a compression test manually. After that change the oil after 600 milled. After that use high milleage oil with Lucas oil. Ans change the oil every 3k milled.

[yoshiki2]

Sorry about grammar but am using my phone..

[speedy25]

When an engine gets "cooked" Its hard to get compression back. Usually the rings take the brunt of it. If you REALLY want to know whats wrong, do a leakdown test. They are MUCH more reliable and informative.

-SP

[michael93LE]

thanks guys, It seems as even with low compression it would at least start, even if it didn't run well. Does anyone know what the compression should be around?

[speedy25]

Compression should be at least 100 to start. 160 is a typical good number.

-SP

[sam333]

As the water ran out and she ( your girlfriend ) kept driving, the engine ( pistons ) got hot, expanded till there was no clearance between the pistons and the cylinder walls. . I bet if you pull one of the pistons you will find galling and scoring. Also when you overheat, blow a head gasket ,you need to check the block for warpage. That could be why your middle cylinders are so low( new head gasket not sealing).Like speedy said 100 to start.