Just become a new owner of a 88 montreo previous owner claims it has bad head gasket, I see no indication of that. Radiator is completely plugged sure that's why it overheats no water in oil and no smoke. How can I be sure about gasket? also doesn't look like oil pressure gauge is working nor temperature gauge same circuit? 212000 miles. Motor is quite and oil looks good.

 

Congrats on your new ride. Don't hurry to pull off the head just yet. You can take a step by step approach. It looks like you are working in the right direction. Check to see if coolant is clean and has no oil in it and vice versa that oil does not have any coolant in it (milkshake color after running engine). Check for any leaks of coolant or oil on the outside of the engine (not from hoses but from the block/head connection area). If all these are OK, I'd think the head gasket is intact. Start by replacing or cleaning out the radiator and flush out the coolant from the engine block. If that eliminates running hot condition - you are done. A weak or broken water pump will cause the engine to overheat as well. You can swap it while replacing the radiator an having the system drained. I'd also suggest you check/replace the thermostat at the same time. Can't tell you about the gauges. Its possible a bad fuse or wire or something else.

 

Welcome, and good luck with your new rig!

 

do a compression test to check the head gasket.

 

after a better look it appears to have a head gasket, to go along with that dash oil pressure gauge is showing low oil pressure. I have mechanic skills, is it a big job rebuilding engine or should I look for replacement. Which is more cost effective?

 

I think the head gasket replacement is not too hard for a person with wrenching skills. You can take the entire cylinder head off and replace the head gasket. Then all you heave to deal with is making sure your timing belt is set up properly. One of the first links on the this forum will get you to the information on timing belts and other useful info. Don't despair. Good luck with your project. Keep us posted of your progress.