I have an engine issue with a 2000 Suzuki Esteem with a 1.8L automatic and 260k miles. Admittedly, the car isn't worth putting much money into, but I'd like to see if I can keep it on the road one more winter. The engine runs great when cold, but after about 20 minutes of driving it will develop a misfire on cylinders 2 and 3 and set a code for that. I swapped the coils and plugs (no help) and checked the compression, it is fair on 1 and 4 and low (about 90 psi) on 2 and 3. It was suggested to me that the head may be warping when hot and to re-torque the head bolts near the misfiring cylinders. As far as I know, they are not torque-to-yield bolts, and a new set costs about $20. The engine head and block are aluminum. My concern is that the threads could be torn from the block if I replace the bolts, and I'd like to know if anyone has an opinion whether re-torquing or replacement of the bolts is better, and could likely fix the problem, or would end in disaster. Thanks!
Jack42, got me thinking...very painful btw! Anyway, check for how much carbon deposits you have on valves (will require some disassembly). Just a crazy idea on valve deforming because of heat (lack of dissipation and hot spots on the carbon).stuck on their backside...yea crazy theory but we're arguably past normal already...
If your head was warping enough to leak compression I'd expect to see it leaking coolant.
Do another compression test but this time put some oil down the spark plug holes.
If the compression comes up it's your rings. If it doesn't come up then it's a compression leak above the cylinders.
Frankly with a 20 year old Suzuki at 260,000 miles, if it wasn't the rings I'd be more suspicious of losing compression through worn out/poorly seating valves than a warped head
It shouldn't and I'm not so sure that's the issue. However, unfamiliar with that vehicle, Did you flush/replace coolant yet? Redo comp check dry vs wet (Scotty has vidy on this).
If you do change head bolts, use a thread cleaner tool on bolt holes and antisiege on new bolts. Insure your torque wrench is calibrated (accurate). Keep us posted.
What was the compression at the other cylinders?
Leak down test would be my next test. You could be loosing compression through the valves and re-tourque won't help that issue.
Have you checked your timing? Timing could have jumped causing a misfire.
