Good Evening i have a 2003 blazer with 140000 miles on it. Lately i have been having issues with it overheating. Temps goes to about 240 then goes back down to normal operating range after about 30 seconds or so. (See Pic).All fluid levels are good and water pump is about a year old and radiator was replaced this pasted February. I believe and hoping its the thermostat since that is cheap and easy fix. What else could be causing this. Not sure if it related but at times, mainly when the engine is still cold, my oil pressure seems to run high. Again See pic. Thank you for any help.

On a unrelated issue, can i just buy the screws the hold the side mirror to the base or do i need to buy a new mirror. I have someone lost 2 of the 3 screws that hold the folding part of the mirror to the base (part that attaches to door).

 

Does it smell hot when it goes to 240? Hook a scanner with live data capabilities to it and see what it is really running. The fluctuation is normally a sign of a low coolant situation. As though you said the coolant is not low.

Does it ever over flow out of the reservoir or sound like its boiling?

What does the radiator look like in side? Could be a clog.

Oil is thicker when it is cold then thins out a little bit when it gets warm. As long as you have 10psi per 1000 rpms you should be good.

 

Usually when temp spikes like that, it means there's an air pocket in the cooling system. Have you "burped" the system and try to add more coolant to the radiator, (not reservoir)?

 

Hook: I haven't tried adding any coolant and have no idea what "burping" means lol.

Hubert: I haven't inspected the inside of the radiator and doesn't smell hot and no smell of coolant. I haven't check fluids level when warm, but when its cold there is fluid in the reservoir. I haven't look to see if it coming out of it or not, nor noticed it boiling.

Its probably related, but i does seem to take longer than normal for warm air to come out of the vents when using the heat setting

Thank you for the tips

 

I'm betting air in the system...

 

To burp it, raise the right front corner of the vehicle. The idea is to get the radiator opening, (where the cap goes on) up high. Remove the cap, bring the engine to operating temp. Quickly jab the throttle a few times, (idle to ~3K rpm) to push any air bubbles out. Hold idle speed around 2K rpm, and add coolant. Jab the throttle a few more times and top off with coolant. Repeat until it won't take any more coolant. The entire time, keep idle above ~2Krpm, then install the radiator cap. A new Stant cap would be a good idea, the OEM caps have "issues". Fill the reservoir to the MAX mark. Check it again in a couple of days and make sure it stays at the MAX mark. These things like to eat lower intake manifold gaskets, and when they do, coolant level will drop, sometimes with no evidence of a leak.

 

is it because of the material that makes them susceptible to getting eaten up?

 

Bagherra, there are several contributing factors of why the gaskets fail.

 

Just want to provide a update to my issue. I believe I have solved the issue. Even thou i could pin point an exact issue, i went ahead and replaced the thermostat and radiator cap. I also noticed the coolant level was a bit low. Will have to keep on eye on this, hoping i don't have to replace the intake manifold gasket again. Had to have it replaced about 3-4 years ago. One thing i noticed is when i went to remove the thermostat housing the thermostat was stuck and would not come out easily (see pic).Is this normal?

Thanks for all the help, it saved me a lot of money, i probably would have paid an arm and leg if i took it to the shop.

 

Pretty normal to stick in the water outlet or the intake manifold. When you had the intake gaskets replaced, if the new style gasket was not used, (Felpro MS98002T) it's very possible for them to leak again.