Koko4

So, the other day I was driving and got about an hour away from my house, and pulled over to eat a Chick-Fil-A sandwich in a parking lot. I left my car running (on a slight incline) with the A/C on. Started to overheat (over 1/2 up the temp gauge). I popped my hood real quick to ensure that both fans were on (they were) and both hoses were hot (they were also). I shut it off, let it cool, and drove it back home. It wasn't overheating while driving at all, or while stopped at lights or anything. Just when I stopped for an extended period of time.

The DAY before this happened, I started to pop the cap to check the radiator level. I heard the "hiss" that showed me it was still a bit too hot to take off, and I closed it up. The next day it did the weird idling overheat thing described above. I burped the system again, and it hasn't happened since. I didn't know if by popping the cap for that split second, if I could have somehow gotten an air bubble into the system, causing it to overheat like it did?

It had done this before a few months ago on a long trip to Chicago. It made it ALL the way to Chicago just fine (no overheating at all). When I got to the hotel, I parked for a minute and it started overheating (exact same as above) and I ended up burping the system and topping it off, which fixed the problem. At this time I also put an OEM radiator cap on it.

After the most recent incident, I rented a block tester and tested for combustion gasses. No change in color, so no headgasket failure.. I also sat there and visually watched the radiator fluid level while manipulating the accelerator cable - the fluid level rises but doesn't spew everywhere or anything like that.

Today, I rented a radiator pressure tester and hooked it up. I posted a video below to show how slowly it's losing pressure once pumped to 15psi. I don't know if this is indicative of a problem, or if I should just leave it alone. I checked all hoses while the pressure was up, and couldn't find any pinhole leaks or anything. I sat there and watched the neck of the radiator, the overflow tank, etc for signs of leaking.

So here's the video:
https://www.youtube.com/watch?v=rW_C...ature=youtu.be

I wouldn't be TOO concerned about it, but I have to drive to Dallas and New Mexico in September so I want to make sure it doesn't leave me stranded.

tony_2018

I guess the next thing to look for exhaust gas in your coolant. It could be a worn out heater hose/radiator hose, clamp, etc...etc..

You have to look around and check all of your hoses for any signs of dried up coolant.

TomCat39

You didn't tell us the year, make, model, trim, and mods of your car.

I know the 92-95's use plastic tanks on the radiator and they do give out over time. It could be the seal on the plastic to metal is giving way, when the car cools it pulls coolant back in from the coolant recovery, if the seal on the rad is leaking it can pull air too.

So your periodic burping temporarily fixes it until it sucks in enough air to cause the issue again.

tony_2018

I tend to skim alot dude, and when I do its like over large amounts of words.

Koko4

It's a '97 Civic LX with a D16Y7, completely stock. I replaced the radiator about a year ago (I believe it was sometime last summer) because it had a hairline crack right under the hose that leads to the coolant overflow tank.

Coolant overflow tank always remains full. Coolant level in the radiator never SEEMS to be low when I check it cold (which is not super-frequently). I am just worried because of the slow drop in pressure (did you guys watch the video?).

When I first got the car (50,000 miles ago - it's at 199,000 now), I was trying to tap a hole for the metal bracket that attaches to the block / motor mount, on the driver's side. The one that sticks out of the block and has two bolts that go horizontally into the engine. Well, one of them was snapped (I extracted that one) and the other was stripped out. In the process of widening the hole to Helicoil it, I accidentally drilled too far and hit a coolant passage. My fix at the time was to use grey RTV and tighten the bolt back down. It's worked for the longest time, but I can't help thinking it could be the culprit here. Problem is, I REALLY don't want to go through the hassle of taking off all the accessory belts / pulleys / PS pump / crankshaft bolt, just to verify this. I tried looking for dripping out of the weep hole at the bottom of the lower TB cover, but no luck. It doesn't seem to be a fast leak (if it IS a leak at all). I'm wondering if this is one of those situations where I could do more harm than good by going back in there and messing with it again. The original fix held up pretty well... I figured I should mention that story because it could have some relevance.

Is there any way to find this damn leak other than using a pressure tester? I have pumped the pressure tester up to 15psi and felt around all of the hoses / coolant overflow / watched the radiator and tried to find any type of slow bubbling or hissing from anywhere..with no luck. How would an actual mechanic find what the cause was if the system, under pressure, isn't producing any visible leaks or issues? It's one of those ghosts that seems to be very hard to reproduce.

TomCat39

I believe you just told us where your leak is.

I would pull that bolt and clean out as much of the grey rtv you used. Then I'd look for Loctite 30558 and use that on the bolt threads and bottom of the bolt. It's PSI rating is much greater than the regular grey rtv and it resists engine fluids very well.

The best fix would be to disassemble where ever you over drilled and fix the hole you made with JB weld. JB weld works well on cast aluminum, if it's polished you have to scuff it up really good. But that I suspect is way more work than anyone in their right mind would want to do.

So I still suggest Loctite 30558. Here are the specs:

Loctite® High Temperature Gasket Maker. Slow-setting, non-hardening, high-temperature sealant. Recommended for heavy-duty applications. Seals up to 5,000 psi. Temperature range is -50°F to 600°F (-45°C to 315°C) intermittent. Resists common shop fluids. Applications include aircraft heating systems, steam lines.

FYI: Clean up is with isopropyl alcohol. And only takes 3 hours before you can put the machine back to use (add fluids etc).

Koko4

The Loctite is a great idea! Do you really think the coolant could be making its way past the bolt threads (and helicoil), past the flat part of the bolt, etc, to the timing belt area? I wouldn't be opposed to JB Weld, but its basically an open hole about the size of the end of my pinkie, at the bottom of the hole the bolt goes into. I wouldn't want the JB Weld to get caked back there and block / partially block the coolant passage. Wouldn't that be a possibility? Since its a coolant passage, there's no real way to get a piece of anything on the backside of the hole to ensure the JB Weld wouldn't just ooze right through. That Loctite sounds good though...do you think I'd be opening a bigger can of worms by trying to mess with it, or by leaving it alone? If I got down to that point and pressure tested the system again, should I be able to see / hear the coolant escaping, to verify that this is indeed my issue?

TomCat39

You said a slow drop in pressure, I doubt it would be noticable.

For JB weld, I would think that would be draining the water jacket and pulling the head so you could access the backside of the hole you created.

Now that the helicoil is in place I'm not sure if you will be able to fully seal it up. I forgot about that bit. Wonder if you can pull the helicoil out without damage, put some of the loctite I mentioned on the outside, reinstall then coat the bolt and install it.

Just doing the bolt may work but I fear air could be slipping between the block and the helicoil.

Still have to drain the water jacket so you can dry up the hole. You can't repair it with coolant seeping out of it while you are attempting to apply a sealant.

I'm assuming you were drilling into the block when this happened. I can't say I can picture where exactly you were drilling.

Koko4

Yeah it could be skipping through that TINY space between the Helicoil and the block..that would suck. I remember it was a HUGE pain to get the Helicoil seated in there right - I had to cut it shorter so it would have the right number of threads. It was a big guessing game. So its kind of a 50/50 chance that I could see no change by messing with it? I'm definitely not pulling the head to access it from the backside. Last time, I had the engine tilted upwards (with an engine hoist) and no coolant drained out. It was still right there, where the hole was made, though, it just wasn't draining out. Not the preferable environment for sealers..

Koko4

#18 or #16 was stripped - I don't remember which one. I was drilling out the hole to rethread and add Helicoil. I drilled a bit too far I suppose =(

Outrun

What radiator do you currently have?

On my 94 Civic EX I had similar symptoms, even with a brand new Koyo C1952 radiator (OEM equivalent). I replaced it with a Go Autoworks all aluminum dual core radiator and drove from California to Wisconsin and back in July with AC running all the time even during the big hills of Colorado and traffic by the Eisenhower tunnel and Vegas and never overheated.

TomCat39

This is a good point.

If you pull both hoses to the radiator and cap them (radiator male ports not hoses) and try the pressure test again, if you don't lose pressure you know it's not the rad. If you still lose pressure at the same slow rate you did before, you can rule out your bolt hole and know it's the radiator.

Koko4

If I take the time to seek out caps / spill rad fluid everywhere, refill radiator and pressure test, then do you think I might as well take it down to the timing belt and ensure that the bolt isn't the culprit? It seems like a messy endeavor to pressure test just the radiator, especially since I don't have end caps / whatever I should use to cap the two male ports.

TomCat39

Knowing me, I would take it down to the timing belt and ensure the bolt is sealed even if just pressure testing the rad but that is just me.

As for caps, Use the radiator hose and connect it from the top to the bottom. I'm not sure if the top hose is long enough or the bottom hose is but I'm confident one of the two can reach both male connectors of the rad.

Also at the same time you can inspect all hoses for any coolant traces. You might just find it's neither and instead one of the other hose connections on the engine that has an issue.

I still would suspect the hole through the block though, just can't get away from that until it's fixed properly. More than likely every few of years you may have to reseal it due to vibration. Maybe with the loctite all the way up to the base of the bolt head it will give you a seal that lasts years.

Koko4

I think I'm just going to bite the bullet and do that. It's been 2 years and 50,000 miles with no issues, so it might be worth fixing it again, and fixing it right. I ordered the Loctite ($22 shipped) from Amazon. I checked around locally and couldn't find it..just Permatex Ultra Grey (which is what I used originally). Once I get that bolt out, I may go to Ace Hardware and try to get the same bolt, but about 1/2" shorter..I think I had to put some washers at the end of the bolt (against the bolt head) in order to not bottom-out into the coolant passage. I will try again with the stock bolt and see if it will bottom out, but for some reason I think I had trouble with it before and that's why I did it this way.

This will probably all take place next week during the weekdays.. any other tips / hints? Should I go ahead and pressure test the radiator, or should I wait until I tear it apart to get down to that bolt?

burnoutboy

iTrader: (22)

Just a thought... if you're going back in there again you should consider replacing the heli coil with a timesert. The timesert cold welds itself to the metal it's threaded into. NO gap, NO leak between the repair and the block.


never been a fan of helicoil on anything important anyway. Nothing wrong with them, they're just not the best option out there.

TomCat39

Take a look at the diagram you posted, one bolt is longer than the other, it looks like you reversed them on the re-install. Ace Hardware bolts probably not equal to OEM bolts. You will need grade 8 at the bare minimum and I'm not sure they will have the proper metric thread pitch.

The timesert mentioned above sounds like a fabulous plan. I've never heard of them but a cold weld to the block is ideal indeed. Then you only have to seal the threads of the bolt with the loctite 30558.

And yes, I'd still pressure test just the radiator to rule that out as a possible cause even if it's only a year old. Could have gotten a faulty one, it happens once a blue moon or so.

One tip is to clean the bolt hole with non-chlorinated brake kleen. It dries residue free and will displace the coolant, oil and most dirt and debris in the hole. What little gunk that will get into the water jacket really shouldn't pose a problem but since you have it mostly apart at this point, a little water flush of the water jacket wouldn't hurt. That will provide a nice surface for the timesert.

For the water flush there is a drain bolt on the side of the block (at least on the 92-95 series, can't see them doing away with it on the 96-00 series) and you can flush water in through the thermostat housing. That is if you are concerned about what little will get into the coolant system via the hole into the water jacket of the block.

Koko4

Ended up hooking the bottom radiator hose to the top, and pressure tested with TWO different testers. Both of them had the same slow pressure drop. Replaced the radiator, and tested again. Now I have a VERY small drop in pressure, but I am attributing this to the tester itself. You can kind of hear the "hiss" from the neck of the brand new radiator.

When I hooked up the top radiator hose to the new radiator, it had a small leak at the connection..I guess I stretched out the old "clamp type" hose clamp too much, and replaced it with the type you screw down the a flathead screwdriver.

I took off the upper timing belt cover and was watching around the mount (what I could see of it, anyway) and my original "fix" seems to be holding up just fine. No drippage, no sign of spilled or sprayed coolant underneath it (checked with a UV light after putting dye in the cooling system). I'm just going to leave it as is, for now! I did end up buying the Loctite gasket maker, and if I ever have to go back in there I will definitely be using that.

As a side note - is it terribly stupid to run the car with the upper timing belt cover off? I know there's always the risk of getting a bit of dust / dirt in there, but other than that..?

TomCat39

It's not advisable, anything that flies in there can be detrimental. People do do it without issues but it just increases your risk.

Glad you found the issue, sounds more like it was the hose more than the rad, sorry you paid for another new rad when it was just a hose. Also glad your original fix is holding up, that's always good news.

Cheers.

Koko4

Thank you! The new radiator was actually the one with the hose issue, once I reinstalled the old hoses onto the new radiator, this seepage happened for the first/only time. The old one held fine with no problems. I replaced the squeeze-type clamp with the traditional "flathead screwdriver-type" hose clamp and don't THINK I have any leakage. Haven't been able to get a great peek at the bottom rad hose, though.

tony_2018

Leaving the timing belt cover off has got to be the most dumbest thing I've seen time and time again. I'm not even sure why people do it, no benefit, nothing cool in there.

Koko4

Yeah now that I'm pretty confidant there isn't a leak at the mount, I'll probably put it back on.. it's so fun to watch, though!