Good morning to all. As some may remember I have a 1994 EX with a 1993 LX motor installed, hence the confusing title. Yesterday my temp gauge pegged. The fan was running full on. Movement did very little to bring down the gauge, although I thought I saw it trying to come down a little when underway, but the ambient temperature was near 106º. When parked, I could hear the coolant boiling in the system. After cooldown, I verified the radiator full. When checking for air in the system however, with the bleeder nipple cracked it would burble, burble, spit, spit, burble, burble, spit, spit, with the spits launching the coolant to the open hood. Granted, she was still pretty warm although the gauge now read below the halfway mark and the fan was actuated. Here is what had already been replaced on the car/engine all about 5 k miles ago
Headgasket
Thermostat
Water pump (with a timing belt)

Any ideas here? She's been rock solid to date.

Help, as always appreciated.

Ed Fisher
Dallas, Tx

 

need to air out the system..

 

Thanks Droopy. I can see now that I re-read my post that it wasn't very clear. My questions should have been more pointed. Since I have been driving the car without incident for quite awhile I would not have expected air to have gotten into a closed system. I tried bleeding just as a matter of course. Would the burble/spit be indicative of a head gasket issue, as in the spit was a compression stroke, or, is it simply not good to try and bleed a system after having been so hot?

 

so it suddenly overheated, then I would just change out the thermostat first.. also does it bubble/spit out from the coolant overflow bottle?

 

I cannot be sure exactly how sudden the overtemp occurred as I didn't notice until the gauge was pegged. I had just gotten off a freeway, made a stop, went inside, came back out and saw the gauge. There is no spitting from the overflow bottle. I will try a thermostat firstly, thanks. I will also re-bleed the system when cold and see if I get the same burble/spit from the nipple and report back. Strangely, the last time that I had a similar issue, as in came off the freeway and the car would then overheat, it was indeed the headgasket. I can only hope that this is not the case again.

Appreciate the responses Droopy.

Ed

 

Okay, car cooled off completely. Fired it up and pressurized the cooling system. So far have changed nothing, just trying to troubleshoot. Opened bleeder screw and had smaller bubbles, but bubbles nonetheless. Not too many, but it took awhile for them to turn into solid fluid before closing bleeder.
Question: How does air get into a closed system?
Brought car up to full operating temperature and drove it, noting temp gauge rock steady just below mid mark. Ambient temp outside 102ºF. Radiator fan operational and running. Parked car, noted both upper and lower radiator hoses to be same temp to touch. This tells me thermostat is open, right? Turned heater on and no heat from vents.
Question: If upper & lower hoses are the same temp shouldn't that indicate that the thermostat is open?
Question: Even if thermostat is open, and no heat, which would indicate a clogged heater core, that would not cause the initial overheat condition as seen on the gauge, right?

I have a new thermostat and a new radiator cap, both genuine Honda, but I don't like throwing parts at a problem without an understanding of the failure.

Question: Am I missing something in this system? A valving or bypass, or otherwise hidden culprit that I am failing to comprehend?

Thanks for reading and staying with me. I promise to post the definitive fix once understood.

Ed
Dallas, Tx

 

Ed, my honda is mysteriously overheating too, however, mine blows heat.

Checking the radiator hoses with your hand is not optimal. The lower radiator hose could be hot because its so close to the block. I would use an IR gun and let the car run for a bit and check to make sure that both hoses are reaching atleast 175 F. If you really want to test your thermostat, remove it and dangle it from a string in a pot of hot water, use a candy thermometer to check the water temp when the thermostat starts to open, it should be starting to open around 170 and should be fully open around 195.

Also, when you replaced your HG, why did you replace it? What was the initial cause of damage to your HG? Did you have your head machined? If not, the same problem you had before could have breached your HG once again.

To know for sure if its your HG, perform a leak down test.

 

>Question: How does air get into a closed system?

Typically, from the cylinders through a leaky head gasket. Get the radiator completely full, start engine cold with the radiator cap off and rev it, see if bubbles come out.

 

Thanks for the replies, I appreciate the help. I did not deck the head after the last headgasket 15K miles ago. It was checked for flatness, which it passed perfectly, but it was not machined. Therefore, it is possible indeed that there is a flaw that was not caught with close inspection that resulted in another headgasket blowing. MK, thanks for weighing in, I'll check for bubbles. Since this so closely resembles the last failure of the headgasket, i.e., intermittent overheating primarily after freeway travel and then shutdown, in town driving, I suspect it may indeed be the same fault. Sheesh. Will update Monday as no internet at the house, save smartphone. Thanks all.

 

Okay, the plot thickens. This weekend I took the thermostat out and it tested good in a pan of water, no surprise there, just wanted to rule things out. Buttoned it back up and started looking for bubbles per MK. It bubbled alright and at one point spewed forth like Linda Blair in the Exorcist. Dang. Headgasket is shot, but why the failure after 15,000 miles? I would suspect that a non-planar head or block would have resulted in a failure far sooner, and those surfaces were checked pretty darned closely when the HG was last replaced. Something just wasn't adding up. Here is what I found.

For all Civic engines, except VTEC, years 1988-1995, I found TSB #97-047. It basically says that the original head gaskets were weak and calls out a replacement part number as well as new head bolts to be used. This makes far more sense to me than any other scenario.

I had already ordered a head gasket set from my local Honda dealer, the same dealer as last time, and it included head gasket p/n 12251-PM5-S02, the faulty gasket. The new replacement per the TSB is p/n 12251-P01-004. I told the dealership of the disparity, and I suggested that they offer a goodwill gesture as they sold me a flawed gasket last time, almost did it again, and that they were not on top of the TSB's sent from their own company. Since it had been 2 years and 15,000 miles, they offered to give me the parts at 1 cent over their costs, which was a significant savings, but I am still not satisfied and have a call into the Honda zone office here in Texas. I found their phone number starting with Honda N. America in California. I don't want anything given to me, but I want to alert everyone of the problems, time consumed, expense, disappointment, and vehicle down time that results from this failure. If I had gone to Billy Bob's parts store on the corner I would deserve whatever I was given and the issues that go with it, however, I go to genuine OE parts so as to allay all of those variables and not have to re-do work. In this instance it didn't work and I'm not too happy about it. Thankfully I'm not out whatever exorbitant costs the dealer would have charged to install the last one.

So that is it for now, I thought I would share and I hope this helps anyone and everyone with this issue. I will post back on the condition of the head/block once apart, but I suspect they are fine, unless I hosed them on this last overtemp condition that I didn't notice until the gauge was already up, instead of on the climb.

Ed Fisher
Dallas, Tx