Page updated on 04-22-2018

Overheating Mystery

09-20-2007, 11:49 AM
I have an overheating 95 honda civic. Coolant fan relay was blown and I believe this caused the initial overheat with white exhaust. Replaced
relay and it still would overheat after 30 to 40 minutes of highway driving but no white exhaust. Also, no sign of coolant in oil. Replaced
thermostat and flushed system (plain water). Also, it would not pull coolant from reservoir so I replaced the radiator cap without effect. Would
still overheat and lose coolant gradually. Coolant pumps out of upper hose when I disconnect it so the water pump must be working. Had another
occasion of white exhaust and running rough. Number 2 cylinder was not firing so I pulled the plug and heard sizzling in the cylinder. After
cooling down it ran fine. Next I used Bars Head Gasket Repair following instructions exactly and cooling system began to pull coolant from
reservoir again but now overheats in just 15 minutes (but no repeat of white exhaust and runs fine otherwise). Compression in cylinders 1,2,3,4 is
120/195/195/150 cool and 195/190/190/210 hot (just below overheat level). Anyone have a suggestion? Could this be a blown head gasket even
with high compression? Could there be coolant blockage in the block yet have the water pump still move the coolant out of the upper hose and
have a good flow of water from heater hose T connector out the radiator when flushing with a garden hose?

09-20-2007, 09:37 PM
rule one never ever use leak fixers because you just made the prob worse. bars and any other head gasket repair has tiny particles of metal in it and you just plugged your radiator up and now you have a blown head gasket just because theres no water in oil doesnt mean nothin because the water is leaking out of the exaust side of the head gasket if u keep driving you are gonna end up buying a new motor. when the coolant leaks out exhaust side of head gasket it gets blown out the exhaust hence the white smoke to be sure if you dont believe me fill up water and start car and put hand over pipe and feel what that white smoke is its steam so now that we know its the head gasket have fun rebuilding it and hope to god the head aint cracked and no parts are warped and have the head pressure checked and machined and have fun rebuilding motor

09-22-2007, 11:40 AM
yep, headgasket... its prolly just a small crack that when the engine is cold allowing the coolant to enter the combustion chamber. when it heats up (of course metal expands) closing the crack and sealing your headgasket...

09-22-2007, 11:48 AM
sorry man but i agree w/e1 you need to pull cly.head

09-24-2007, 09:05 AM
Thanks for the input but before I spend the time/$ on the job I just want to make sure. Leakage into the cylinder on a couple of occasions was obvious from the steam in the exhaust but it may be just from the high pressure and abnormal expansion of metal from the high heat, resealing at normal temps. Radiator flushes fine so it isnt plugged up with the fibers or ceramic particles from the Bars. Not sure about flow through the block. I guess my main question is about the compression readings. Can I still get high readings even with a leaking head gasket? Also, some people in another thread said that a blown head gasket pumping exhaust gases into coolant (creating the overheating) would show up by the upper hose become hard, which mine does not do. Any ideas on the compression before I start tearing this thing apart?

09-24-2007, 01:18 PM
let it sit for a couple of days then pull your spark plugs and see what they look like if they are rusted then thats your answer right there pay attention when you take them out because that will tell you which cylinder has the prob. and as far as compression there should be less than normal i think normal is like any where from 150-180 psi depending on car and motor but look in your chilton manual if not any manual and it will tell you the compression

Add your comment to this topic!