joeblo223

Ok tried to change whole ignion system when it didn't work I tried a compression check on cylinders 1 and 2 and got between 35 and 40 lbs witch is way under what it should be I took off the timing chain cover all the notches line up and the belt looks good what else may cause this I was thinking scince it happens when it was single digit tempsit could be freeze plugs . Wasn't sure if freeze plugs would cause low compresson

87blackbeauty

I've never seen freeze plugs determine compression. Did your engine also puke out coolant? That'll happen when freeze plugs are pushed out. But compression is determined by the pressure created in the cylinder between the piston and head. Likely places for leaks and loss of compression are piston rings, head gasket, and valves. Or a cracked head/block. If your radiator was filled with water more than antifreeze then I hate to tell you, but you probably are going to want to look for cracks and replace whatever cracked, be it the head or block. Since it's a v6, I'd compression test both sides and if one's good, look for an issue in the other. If both are bad, then maybe it's a block issue. I don't know. I've had poor or no compression twice. Once for an obvious blown head gasket, and once for bent valves. There are rarely freezing temperatures where I live, so that's the best I can do. Hope it helps and good luck.

scope103

It's not the freeze plugs. If you run out of antifreeze and let the coolant freeze solid, the freeze plug is supposed to push out before the expanding ice actually cracks the block. If you had pushed out a freeze plug you'd be standing in a pool of coolant.

As 87blackbeauty says, low compression can be caused by rings, valves, head gasket, and about a half-dozen other things. Sometimes low compression on adjacent cylinders (e.g., 1 and 3) hints at a cracked block between them, but yours (1 and 2) are on opposite sides of the block.

While two bad cylinders are going to hurt power, it would probably still start on the remaining four. But when you changed the "whole ignition system" it didn't work. Meaning you've still got no spark? It will be hard to help you on compression issues if the ignition is known-dead.

ddv1126

I had this problem. Turned out to be a bad coil.

joeblo223

I have spark the ignition system is fine I think the problem is with compression