slowZ6turbo

First off, I would like to personally thank anyone taking the time out of there day to read this and lend some healthy knowledge!!

I will try to make this as descriptive and accurate as possible, if I fail to do so in any way I apologize in advance, I am new to this forum, but not forums in general. I actually migrated from another forum that unfortunately holds more disrespectful ricers than actual Honda enthusiasts.

Okay enough of that, here is a description of the car, a list of things done to the car, and then next I will map out a timeline of the symptoms problems and repairs I have dealt with so far.


I have a 94 civic ex sedan, with the original d16z6, I bought it from the original owner and it was stock right down to the intake. it had 175k miles on it, but was serviced at the dealer its whole life with oil changes tune ups etc, the head gasket, timing belt and water pump were also replaced at 125k miles by the Honda dealer.

Shortly after the unexciting acceleration got to me... I pieced together a turbo setup, here are the specs:

-hondata s300 v1 in a p28

-catch can setup using 5/8 bung on valve cover, open breather at PCV and black box delete fitting to 5/8 line to the catch can.

-brand new garrett 60 trim

-ebay log manifold with synapse synchronic wg

-walbro 255, 330cc injectors, b&m fpr and gauge

-3" straight pipe with long resonator

-plugs 2 steps colder gapped to .28 (BKR7E-11)

-Tuned by performance and styling. 218WHP at 10.8 lbs of boost.


I did a compression check prior to the turbo and I got about 185psi per cylinder with a variation of 1psi or so.


My first issue was about 2 months ago, an audi s4 was tempting me on the highway doing flybys and coming back to hang with me. I was curious what my car would do and was on a dead 3 lane highway (I do not support nor am I bragging about street racing) So at about 65 I dropped to third, he pulled alittle as I spun but then I surged past the s4 and hit fourth, at about 6500 rpm I got a CEL and noticed the temp gauge climbing, I immediately hit the clutch and shut the car off and turned the key back to ign for the wheel lock. I waited 10-15 seconds or so and turned the car back on, it immediately went to normal operating temperature.


I replaced the thermostat with a stant 170 degree, also bought a new OEM radiator and cap plus fresh coolant. I flushed the system, jacked the car up high as I could, idled with the radiator cap off for about 15 minutes and then used the bleeder valve to rid of any extra bubbles. It seemed to work, but had little to no pressure at the bleeder valve, not sure if that is normal or not.


The car will NEVER overheat at an idle, it can idle for hours even with no fan which is very odd, at this point it never overheated on back roads, even doing hard pulls through first and second. It only overheated under consistent heavy load on the highway. Using a laptop with s300 to check temps, I idled around 172 degrees. Regular driving I see 185-195 degrees, highway driving it holds steady at 208 degrees cruising at 55, as soon as I try to cruise around 70mph It will almost immediately overheat reaching up to 260, but then cools down as fast as I can shut the car off and coast for 10 seconds and turn the car back on, then if I maintain 55mph or so it has no issues at all!


I did another compression test, and yielded the same results as before the turbo. Oil is VERY clean and so is the coolant, no smells of coolant at all when overheating, and never had any issues with hoses bursting or any symptoms of high pressure.

I went up a 10% grade in fourth at 2k RPM and held it at WOT to create some heavy load, I held it for about 15 seconds and it did not overheat right away, I let up the throttle to about 30% and then noticed the gauge creeping up from half. This showed me it overheats under load, and not due to RPM. I have no front bumper right now and I assume the overheating on the highway is worse because of aerodynamic resistance.


At this point the possibilities from my knowledge/experience include, head gasket, water pump, air bubbles, clog in the system somewhere or even a faulty ect sensor.

Head gasket is tough because the compression is great, there is no loss of coolant or oil, and no oil/coolant mixing of any kind and it never starts hard, and has not had any signs of breaking up or power loss.

Waterpump makes no abnormal noises and does not leak at all, and I would assume if it was cavitating it would be RPM based and not load based.

Air bubbles is a possibility but I think I did a very good job bleeding the system. And also a clog is possible, but my lower radiator hose gets hot, and my heat works good. So it would have to be a very tricky clog.

ECT sensor is a possibility but do not know how load would effect it. Maybe as the temp naturally rises under load the sensor is unstable at the higher voltages? But also, I read there was two sensors, one goes directly to the dash gauge and one to the ECU, if that's the case, both are showing signs of overheating so it would be hard for the sensor to be the issue in my situation. (considering what I read was correct)

The main clue here is that it cools down so fast. In past experience when a car gets to a temp that high it usually takes 3-5 minutes to cool down, not 10-15 seconds. So I am holding onto that for dear life because its too cold and snowy in the northeast for me to be doing a headgasket/waterpump right now!

Before the turbo, I never has an issue with temps AT ALL, and I am a very spirited driver. Even on the dyno after the turbo we had no issues at all. I can go drive the car right now anywhere off the highway and never deal with overheating.


I know there isn't much to go on, and its a very vague issue at this point. But I am hoping someone has had a similar puzzling issue and can lend some advice.

slomofo

iTrader: (1)

Cliffs:

Car overheats when cruising 70mph
Doesn't overheat any other time.
Fans don't come on at idle.




You seriously could've written that in those three sentences.


Do your fans work at all? How close to your fan is your turbo? Have you tried cleaning your radiator? How old is your water pump?

slowZ6turbo

It overheats mostly above 70, but like I said it overheated under constant load at 2k RPM on back roads as well. And the fan works fine, initially it did not because the variables were not setup in my ECU. I set it to kick on at 165 degrees and now it works fine. But before it never overheated at idle with no fan working at all. The turbo is about a foot from the fan/radiator but the downpipe is about 3/4" away from the side of the radiator which I thought could be an issue so I heat wrapped the downpipe but it made no difference. And like I said earlier it is a brand new OEM radiator I bought and replaced it after the first time overheating, and the water pump head gasket and timing belt were replaced at 125k miles, it now has about 175k miles.

slowZ6turbo

No one??

Former User

What CEL code was thrown?

When you bled the cooling system, was the heater valve on the firewall wide open?

slowZ6turbo

Thanks for the response! It was a code 11 Which is overheating protection paramters within the hondata s300 ECU. And yes the heat was on full

Former User

Rent a Block Tester kit from AutoZone.

Jimi Hondrix

"unfortunately holds more disrespectful ricers than actual Honda enthusiast"

I note a fart canny type disgust exhausting from your statement.

slowZ6turbo

The disgust is a lot deeper than just the fart cans haha.

slowZ6turbo

Just youtubed what it is, Good call! In all my years working on cars I never came across that tool yet. So basically it will decipher whether I have a head gasket issue that is not effecting coolant/oil ports, for 25 bucks I am going to head there today and just buy it. Wouldn't be a bad tool to have in the tool chest.

I will update with results within a few hours, I appreciate the advice, and pray that I do not have combustion gases in my coolant!

Former User

Free rental of tool at AutoZone - just pay for the test solution.

A positive result means the head gasket is blown.

Unfortunately, a negative result does not rule out a blown head gasket.

slowZ6turbo

So its bad news or no news HAHA. Atleast its something! And atleast a head gasket is very easy in these, and will be my excuse to throw in some HC pistons/eagle rods and bring down my boost some. Would enjoy some nice low to midrange power before boost.

timetosleep

Hey this may sound a little crazy btw! so I think you are on the right track, thermostat won't be the problem nor the radiator, the sending unit that controls the gauge can get "lazy" and give inaccurate temp reading but like you said the odds of both being wrong are slim to non, that leaves you with the head gasket, now this is where my comment might get weird, If the head bolts are not torqued down to spec "for some reason" but they are tight enough create a seal when vehicle is cold or not under load it would run fine, however if their just enough out of spec it could cause the head to lift of the block just enough to let exhaust gases into the coolant passages that might explain the quick rise and drop of coolant temp when the motor is under/no load, check the torque of the head just for haha's if not than it might be signs of a head gasket in the beginning stages of blowing, I've actually seen the whole head lift thing happen before but it was on a MR2, hope this helps, you're on the right track tho, keep an eye on that head gasket.

slowZ6turbo

Not crazy at all! I have learned over my years of diagnosis and repairs that anything is possible, so don't rule anything out!! But re-torqueing the head to factory spec will be my last resort, its super cold and expecting a few feet of snow. But the more I get into this the worse it looks!

slowZ6turbo

Okay so this has just been a total nightmare, autozone had the tool but no fluid, went to advanced because the website said they had it, but they did not. Went to napa, and missed the close time by a couple minutes. I then had to drive to the next town over to get the fluid.

On my way home it started overheating slightly, and I was being extremely cautious while driving it, light throttle, and low load. I got home to do the test, and noticed I could not visually see coolant, and it took about a quart and a half of coolant.

I went to do the test, and the damn tester is clogged because it wont bubble with the aspirator, its just plugged solid. I did however take it for a quick test drive after adding coolant and it did not overheat at all, I have it some steady load at about .5-1PSI of boost and it never overheated at all. Now I have a lot of variables against me and possibilities. Tomorrow I am going to return the test kit and grab another one and try it again. Also I will check for coolant leaks, or evidence of coolant being pushed out of the overflow and hopefully get a better picture of why I was low on coolant.

Former User

Good plan. You also may want to pressure test the cooling system.

timetosleep

Man I lived in Connecticut for a while and I hated the winters so I hear you there lol, I know you said the oil looks good earlier, can you check it again? Just to make sure, if no coolant in oil that means it's probably going out the tail pipe, you might smell a sweet smell from the exhaust also I know it's hard to tell in the winter up there due to the temp, but if coolant is being burnt than you should have white smoke like coming out the exhaust, this would happen under load and the engine at operating temp, not cold at idle which is normal in cold weather, hope this helps, just as a thought btw, I'm not the most knowledgable on turbos however I know some are water cooled, is it possible for a internal leak in a seal inside the turbo causing coolant to leak into the intake, or boost to leak into coolant system? to me this might replicate head gasket like issues but it's actually in the turbo? I figure the vehicle doesn't seem to overheat until load or boost right? Not sure if possible but also worth checking I think.

slowZ6turbo

Yep and call me crazy because were moving to upstate NY soon, where its even colder! But CT the cost of living is outrageous Making the move I will be able to cut expenses in half which means bigger Honda budget LOL As far as oil, because I am turbo and I have dealt with oil lines bursting and the dummy light NEVER works for oil pressure, I check it every morning and every night, still crystal clear. And I checked it right before I did the test since I was under the hood anyway. As far as the turbo, it is oil cooled only, but if it was liquid cooled that would be an excellent theory and solid possibility. I had a turbonetics super 60 before the garrett and it pushed oil out of the hot side and cold side and also was pushing boost into my oil pan. That is why I went brand new and not used. Ill never buy a used turbo again!

timetosleep

Yeah I hear you on the cost of living in CT so I moved down to Myrtle Beach SC where I don't have to deal with the cold as much as y'all do lol, anyhow I just did some research on turbos and I don't think that will be the issue because coolant passages seem to be in the casting of the CHRA and they don't have coolant seals so I actually think you can write that off but it was a thought, the more I think about it it sounds more and more like a head gasket to me, good luck with the move, anything to get more honda money lol

liam821

Sounds like you need a leak down test...

slowZ6turbo

Hey sorry guys, been super busy and with the damn snow storms every other day I haven't been out much to work on the civic. I did do the block leak test, 3 times and it passed all 3 tests. Oil is still clean, coolant is still clean. I did however pop a heater core hose on the highway, started overheating and got to the side of the road, luckily the hole was right by the clamp so I just cut a few inches of hose and clamped it back on, I had just enough coolant to get going. Hasn't overheated once other than that, I did have one weird episode though. I opened it up and the heat stopped working immediately, just ice cold. Was slightly low on coolant and after adding coolant it seemed to bubble at an idle, not sure if it was boiling or bubbling due to pressure. I parked it and haven't touched it since, waiting for the snow to dissipate a little!

JarvisW

Bubble in the filler neck with the cap off?

Bad head.(or gasket) :/

If you rev the engine with the thermo open and watch the fluid in the neck and it fizzes or bubbles that's the problem, unfortunately.

slowZ6turbo

that's what I was afraid of! It did take quarter gallon of coolant, so I was hoping it was just boiling or something from being so hot. It is like 30 our today and finally isn't snowing, so I am going to drive around and get it warmed up with proper coolant level, and if it bubbles then, I guess I have my answer!!

tony_2018

So it overheats when running but doesn't when idle. Sounds like the head is not bolted down to spec. In my opinion, if you're going to boost get those aftermarket head bolts, new gasket, and torque down to there specs.

10lbs of boost on a car with 175k you gotta expect it and prepare for it.

slowZ6turbo

As soon as were done with this move that is the plan, its tough right now half my tools are packed and its been super cold out. I would prefer to do at a slow pace and not rush through it. It hasn't overheated in a long time, and I went for a 2 hour highway drive, opened it up, did some hard pulls off the highway and took the radiator cap off and NO bubbling at all at idle or when revved. I think the coolant was just boiling because it was low in the radiator and the metal was HOT. It has passed the combustion leak test 5 times and compression test 5 times. All cylinders are at around 185-190 psi. I think in the beginning my radiator was clogged, and after I changed it, it was too cold to suck in enough coolant to top it off, after I added more later it's never had an issue since linked to overheating or head gasket. I will do the preventative maintenance anyway so I can upgrade the rods, bearings, pistons etc and go high compression turbo. I like the z6 because its disposable, there dirt cheap and easy to build!!

Anyway, thanks everyone for your responses and advice!!