Overheating - At a Loss

willy0505 · 07-01-2009

This is an update to a post that I previously had about my 93 Civic overheating:

I recently got into my civic and it had been sitting for about 4 or 5 days and cranked it up and started driving. I looked down after about a mile and my temperature gauge was pegged at high. I immediately pulled over, checked the coolant & it was fine (i.e. not smoke, pinging, steam, etc.). So then I let it sit all day and night and checked the gauge with just power to the instrument cluster (via a 2 click key / ignition turn) and the gauge pegged out at high again. So here are the things that I have done to try and correct the issue:

1 - Replace the Coolant Temperature Sender (the sensor with 1 connector that sits right below the distributor)

2 - Replaced the thermostat (after a drain prior to pulling thermostat and then refill of engine coolant after replacement ensuring a proper bleed using the bleeder bolt - pretty sure)

3 - Replaced the Cooling Fan Relay (in the underhood fuse box)

4 - Replace the Radiator / Cooling Fan switch (thermostat housing) - and i now have confirmed that the fan comes on and does its job

So now what i find is that i can ride down the road for a bit and the gauge will start to increase ever so slightly about 2/3 the way on the gauge on the high side - like after driving about 45 mph (now my speedometer does not work due to a faulty VSS - another issue though) but then when i slow down it will drop down a little bit to exactly half way on the gauge.

So after all of this, i try to run the compression test and i see that a few of my spark plugs are covered in oil.

If anyone has any ideas - i would love some help - i have even tried a different thermostat to ensure the temp specs were consistent with Honda OEM....The problem is that before vacation, the car ran fine, then a 5 day sit and it does not run fine???

Here are my questions:

1 - Should i look into replacing the radiator?

2 - Do i need a new water pump or how do i even check that?

3 - Does this sound like a bad head gasket or valve cover seal?

thanks in advance for the help - i might turn into an average mechanic after all of this....

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gearbox · 07-01-2009

all your ideas are possible. radiator may have a clog, preventing proper coolant circulation and cooling. when you run the car til it starts getting hot, what do the two radiator hoses feel like? on a hot day, both should be hot, but the upper hose should be much hotter than the bottom. if your bottom hose is nearly cold or barely warm, you have a coolant circulation issue with the radiator. bad water pump can also cause this problem. you definately have bad valve cover seal (actually its the spark plug seals which are part of the vc gasket) if you have oil on the plugs. headgasket is hard to say, usually signs of a blown gasket are hard starts when cold (misfires), burning coolant that seems to disappear without a trace, white deposits on spark plugs, and possibly white smoke from exhaust or deposits in exhaust pipe and muffler. i doubt you blew the headgasket with the car just sitting there tho, unless it overheated too much and warped the head.

willy0505 · 07-01-2009

To answer your questions:

1 - Both the top and bottom hoses were hot, so i know that the coolant was circulating

2 - I will check for the white smoke tomorrow once again when i have someone to watch, but i do recall some white smoke the initial time that i cranked it (but keep in mind that it sat for a long time - even though i say 5 days, i was on vacation and it could have more been like 10). I had to tap the gas pedal a pretty good bit to get it to start the very first time when i returned from vacation.

But i do not recall noticing the white smoke since then (i have only driven it after performing some of the things above - i.e. test drives only - no more than 4-5 miles). The car has now sat for about a week, so when i crank tomorrow, if there is water in the head, it should for sure show white smoke with all of that time for water to leak.....

Also, would the bad valve cover seal lead to the overheating issues? I am not an expert by any means, but i cannot envision a reason why that would happen.

Thanks for your speedy reply and suggestions. I will take all of the help i can get....

willy0505 · 07-01-2009

1 more thing - could all of this just be the result of my ignition timing not being set properly? I did have to take the distributor off to get to the temperature sensor. If i did not set it exactly back correctly, could this be causing my problems?

gearbox · 07-02-2009

yeah actually, it might be. if you removed the whole distributor, theres a good chance the timing is off. the valve cover gasket should not affect anything. hopefully the timing didnt permanently mess up the engine. i would have that checked right away.

willy0505 · 07-02-2009

Just as a follow up to the timing question - I retarded the timing a little this morning and that did not seems to impact the overheating, so i dont think that is the problem

I also ran the compression test this morning....when turning over 7 cranks, each cylinder is at approx. 160 (give or take 1)...when turning over 10 cranks (i.e. max compression) - each cylinder is at about 170, so i dont think it is a head gasket....

I tried the bleed again by letting the engine warm to normal temperature and then use the bleeder bolt to get any air out...i just accelerated the car until a steady stream of radiator fluid came out, so i dont think i have an air bubble....

I also read a lot of forums that said to check the coolant at the radiator neck for bubbles for signs of a head gasket issue and there were no bubbles there either, so not sure...

what is next???

gearbox · 07-02-2009

could be the water pump, but im not really sure anymore. all the major causes seem to be okay. i wonder if the actual temp gauge is bad and maybe youre not overheating.

willy0505 · 07-02-2009

Ok after everything that i have done above, i replaced the radiator today and still my temperature goes a little over halfway (i would say that it never goes above 2/3).

So after all of this, i am thinking maybe the new temperature sensor has caused the gauge to read differently (Gearbox suggestion), so i put a thermo in the radiator neck and when the gauge was exactly exactly halfway, the temperature was 190 degree F......

So here is my question, is it ok to drive if it never goes above 2/3 with a dead middle reading of 190???

gearbox · 07-03-2009

well the temp gauge is really not very accurate. the 1/2 way reading could be anything between 140-240F. the gauge is really just a simple way of saying the car is fine or its overheating. 195 is the average coolant temp under normal conditions so i would say you are fine. did you get an oem temp sensor? or aftermarket from auto store?

willy0505 · 07-03-2009

I actually got one from autozone....but i now i am looking into replacing that gauge...do you know of a gauge that i can use to plug into the existing hole for that temperature sensor that is relatively cheap since it is a 93 afterall....that will measure the temp in actual numbers??

gearbox · 07-03-2009

well you must keep the original sensor because the ecu uses it to determine car functions. if you add a water temp gauge, it will have to use its own sensor installed somewhere in the coolant flow. check egauges.com