So I drive a 2000 Honda crv, I did an engine swap with an engine from the wrecking yard about 4 months ago and did a head gasket replacement about 2 months ago. I was driving the other day for about 30 minutes or so and noticed my temp gauge creeping a bit above halfway, (it always rides right below half) so, I started to pull over to check my coolant level. then I noticed when I pushed my clutch in my oil pressure gauge came on. So I stopped and turned it off immediately. I had plenty of coolant in my res so I was pretty confused. I was in an area with no signal so I waited a while to let it cool off and kept driving, taking it easy. I didnt see the oil pressure light come on again at first. Then when i started driving again and the temp started going up the oil pressure gauge came on once again, i noticed that when i have it in gear it doesnt come on at all, but as soon as i pushed the clutch in or put it in neutral it would start to come on. I also noticed the temp would actually go up more if I pushed the clutch in. I got to a point where i had signal and called a ride and tow. Any ideas on what it could be are appreciated 
I’d check oil pressure with mechanical gauge. First.
Did you machine head? Check for cracks?
Car ain’t worth much. But it is nice to have a running car.
Pushing on the clutch pedal causes a low oil pressure warning? hmm … definitely an unusual symptom. One idea, pushing on the clutch pedal, believe it or not, that actually pushes on the crankshaft, pushes it toward the front of the engine. There’s a special purpose crankshaft thrust bearing that is supposed to limit how far the crankshaft can move forward. Maybe that thrust bearing is worn out and this allows the crankshaft to move enough to affect the engine’s oil delivery pathways. I know this is not what you wanted to hear, but just an idea.
Did you reuse the old head bolts??
Didnt machine head just took some fine sand paper to it, wasnt a big blow
Nah new new head bolts
Using sand paper is not the ideal thing to use as you can sand dips into an already warped head… At minimum, use a large Bastard File and angle it multiple different ways…And if you are showing high/low spots then it needs to be machined and always have an aluminum head pressure tested for leaks/cracks… We call it deck and check in my area anyway… And you can also use a straight edge and feeler gauge to check for warpage, this should be done 1st…
The over-heating part of the problem could be something simple, like a faulty cooling system pressure cap. Before spending money and worry-time about the over-heating, suggest to try replacing that part first. If it still overheats, the next step is to pressure test the entire cooling system.
Is there any way to isolate this to tell if its the issue other than taking the whole thing apart and looking at it / replacing it?
Of course… Put a dial indicator on the end of the crankshaft, then push the crankshaft firmly away from the dial indicator (use a screw driver to pry between the flywheel and cylinder block), and zero the dial against the end of the crankshaft. Then pull (use a screw driver to pry between the harmonic balancer and the timing cover, careful to not damage/break anything) the crankshaft firmly back toward the indicator; the dial reading should not exceed the service limit.
Crankshaft End Play:
Standard (New): 0.004 - 0.014 in. (check your service manual to make sure those are the correct specs)
Service Limit: 0.018 in.
If the clearance is over the service limit then replace the thrust bearings and recheck, if still out spec then replace the crankshaft…
Ya, my used motor needed head gasket and crank/bearings. At least block was not ventilated. 23 yr old car. Bandaids. If I made more money i could get a newer/nicer car.