Performance Questions (please don't laugh!)

[peaceofmindinhim]

Hello all,

I'm back with some more questions about my amazing Infiniti Q45.

The other day I was driving home from the gas station, talking with my Mom on the phone, and I looked down and saw my temp gauge was on H. I was about a tenth of a mile from home, so I got home, and shut off the car immediately. I popped the hood and saw the engine had definitely over-heated. I also saw the overflow tank was really really low. I also had white smoke pouring out the exhaust pipe, so immediately I assumed I had a blown head gasket.

I let the engine cool, and then filled the overflow tank with water (i had no coolant), and then decided I should probably get premix. I purchased 3 gallons of premix and filled the radiator with about 2.5 gallons of 50/50 premix. I started the car. NO WHITE EXHAUST. In addition, the car did not overheat.

After letting the car sit for awhile and once I was assured it was not going to overheat, I started to drive it. I put it in reverse, and it SHOT like a rocket out of my driveway. In fact, when I put it in drive, the thing SCREAMED like it did when I first bought it.

Is this normal? Would merely filling my radiator suddenly increase the horsepower? I will say it's been nice having the Q45 be a rocket again, although now I've noticed my mpg has gone down a bit. Is this because I'm taking full advantage of my newly found rocketcar??

Thank you for taking the time to read, and I realize I may be asking a seemingly dumb question. I'm not a tech. I just own my Q45 and I really enjoy it. Thanks in advance for your replies.

Eric

[lino]

I don't have an answer to your question, but I have a question for you..where did the coolant go? Have you had to top off since?

[Infinitiguy19]

The Engine Control Unit does retard the timing and enrich the air-fuel mixture to keep things from melting.

I think you should look at the under plenum hoses for signs of leaks.

[peaceofmindinhim]

Yes, I have had to top off since. There must be a leak somewhere (obviously). The good news is, I don't think it's burning off during combustion, since I would notice other symptoms, correct, such as overheating on a regular basis. I'm getting it pressure tested tomorrow.

[paranoidjack]

I know what to tell you, but I'll pay you $20/gallon for that water you got!

[peaceofmindinhim]

@paranoidjack - you know what to tell me, or you don't know what to tell me?

don't keep me hanging lol

eric

[qship96]

White smoke out the exhaust generally means you were burning coolant, especially if it is low again after you refilled it .......99% your engine is ingesting and burning coolant...........time will tell

[peaceofmindinhim]

qship96 - i agree with you, however, this has only been a one time thing - the smoke only happened when i was completely bone dry, however, it hasn't happened since. if i was burning coolant, especially since i've refilled the radiator, wouldn't i be having white smoke all the time?

[Infinitiguy19]

We can go back and forth all day and night but a coolant pressure test will show everything.

I pray that your engine doesn't need a rebuild.

[Q451990]

There are testers that will show combustion by-products in the coolant to confirm if you have a head gasket leak. A substantial leak would cause frothy milky looking oil.

Heath

[Infinitiguy19]

According to NORIA those oil tests are not 100% but yes that may confirm it.

Change oil first then send run for say 1000 miles and send that 1000 mile old oil to Black Stone Labs.

[peaceofmindinhim]

Ok, first off, thank you to everyone who replied. After some more diagnosis (and some more education on everything), this is what I have to report:

Topped off radiator with 50/50 premix and let the car reach normal operating temperature. I then kicked on the A/C and set to Max at 65 degrees. I let it run for a bit, to increase the cooling load.

I gave it a few minutes, didn't see anything, so I decided to drive to the gas station down the road. When I pulled into the station, I looked under the car, and sure enough I had coolant leaking - drip drip dripping away.

I also popped the hood and noticed a bit of coolant leaking from the cap, not a lot, but it was starting to leak. On the way home, I started to hear a gurgling noise from under the hood (this is new, and has only happened this one time to my knowledge). It happend for about 10 seconds, and I was about 1000 ft from my driveway. I pulled in, and noticed coolant fluid had definitely leaked from the cap, and was resting on the cap, and the nearby areas (fan, and the plastic cover in front of the engine).

I then let the car rest, and then drove it a few miles to my new apartment, No gurgling at all now, but definitely losing more coolant through the radiator cap.

So that's where I stand with the coolant leaks.

My original question remains though: Why is it whenever I top my radiator off with coolant fluid, it screams like a rocket, but then about 20 minutes later, it stops running so amazing?? Is this related to the loss of coolant, and or pressure (since apparently my radiator cap can't hold the required 13 pounds of pressure).

Thank you very much for your replies!

Eric

[yodawill2000]

Replace cap and see if you have a knock sensor code stored.

[Q451990]

Your perceived difference is probably related to the fact that you opened the hood and did something to the car. Mine always drives "faster" after an oil change

That or your ECU is enriching your fuel mixture to try to keep up with the overheat when your coolant leaks to a certain level as Paul suggested. I would concentrate on fixing the actual leak(s) and go from there.

Heath

[peaceofmindinhim]

@Heath, thanks! But definitely not a perceived difference. I would have to agree with Paul, it would have to do something with the ECU, it's happened too many times not to be something along those lines.

Off to buy a radiator cap - will let all know how things go.

[peaceofmindinhim]

Radiator cap purchased and installed - no more leaking from the radiator cap.

System was pressure tested - no blown head gasket.

Apparently my radiator is leaking a bit, but the primary leak is the bypass hose.

I've decided to replace radiator and bypass hose, upper & lower hoses, thermostat, and valve gasket cover. Am I missing anything?

Eric

[Infinitiguy19]

Depends on how many hoses you want to replace (As far as missing something).

Infiniti Of Scottsdale sells a kit that has the upper and lower radiator hoses, Thermostat, cleaning solution and something else for a decent value (Can't remember the price and it changes often).

[peaceofmindinhim]

Found a Q45 radiator at 1-800-Radiator - $155.00 w/ tax
Hoses (upper/lower/bypass) + 3 GAL coolant - $75.00
Labor - $100.00 (a buddy of mine is doing it).

Does that sound about right?

[lino]

Wes bought a radiator that he was pleased with:

post5674831.html

Other threads you might be interested in:

g50-under-plenum-hose-replacement-dial- ... 12964.html

g50-plenum-hose-diagrams-t217467.html

[Infinitiguy19]

Found a Q45 radiator at 1-800-Radiator - $155.00 w/ tax
Hoses (upper/lower/bypass) + 3 GAL coolant - $75.00
Labor - $100.00 (a buddy of mine is doing it).

Does that sound about right?

Well the labor is a bit high and I would do it your self rather than have a friend do it. Does the friend own a shop?
I know a guy who was screwed by a friend of TEN years so I guess I am biased.

Hoses sound spot on assuming your getting this: http://www.infinitipartsusa.com/partloc ... logid=3221

I would go with a good radiator like Wes has and Lino suggested. But I must be fair and say I have never herd of 1-800-Radiator before, just that the name sounds cheap.

I live by this: If your going to do something, do it right or don't do it at all.

[peaceofmindinhim]

Paul,

I appreciate your continuing help. Every shop I've taken it to has told me it's a 6 hour job according to their labor books because the manifold has to be taken off (that's what they are telling me). One place quoted me $750 ($180 radiator/$75 hoses/$30 valve gasket cover and $465 labor), so I assumed $100 was cheap. I am absolutely not mechanically inclined...I wouldn't trust myself to replace the radiator. I do realize I should learn sometime.

Eric

[peaceofmindinhim]

In addition, that COOLKIT you linked, Paul, looks perfect, but does not include the bypass hose, which is what is leaking. It does not appear they have that part..

In addition, will I have to replace anything else besides the valve gasket cover/upper & lower hoses/bypass hose/thermostat

[Q45tech]

BE SURE to replace both the filler neck and rad caps periodically because the rubber seals will fail and leave you dry.

[qship96]

if by "bypass hose" you are referring to the coolant hoses under the plenum, it is a long tedious job that almost always includes replacement of all other old hoses{about 35 of them} under there, as well as the knock sensors.....about $1000 in parts alone and 6-7 hours labor for someone who has done it many times- I would NOT let a "friend" who wants to make $100 touch this job....too many things to go wrong

[peaceofmindinhim]

Every shop I took it to said it would be somewhat of a tedious job, but never mentioned having to replace 35 hoses. The "Friend" who is doing the replacing is a certified mechanic who used to have his own shop, so it's not just anyone.

[lino]

Did you have a chance to look at the threads from my earlier post? That will give you an idea of what "35" hoses qship96 was talking about.

When I had my leak, it was one small hose that was 3 inches long sitting under the plenum. When I replaced it, every hose that was in the way or around it all shattered into pieces. I was prepared though and had bought every hose because I was warned that this would happen by our fellow members. When I asked some certified mechanics how much to replace the 1 hose to stop the leak, they only quoted me the labour and never quoted me any parts prices thinking they could just replace the 1 small hose and that nothing else would go wrong. The reason for that is because they never did this job on a Q45 before and had no idea what they would be in for. I hope you're much luckier than I was.

What's the mileage on your car?

[Infinitiguy19]

Peace Of Mind In Him I forgot about the hose under the plenum but if the guy can do all that for $100 let him.

Honestly though take my advice about mechanic friends because EVERYONE wants money today, Its rare to find nice people!

[qship96]

I dont want a nice person, or even a good friend to touch a plenum job on a Q.....I want a tech who has done it 100s of times......even then, a few small slip-ups occur, as even the famed Byron at T3 missed reconnecting a vacuum hose and 2 clamps while doing my plenum hoses, and he has done more of these than 99.9999% of all technicians out there.

[lino]

All this talk about plenum hoses just brought back some memories and I'm getting anxious and will probably have nightmares tonight. I was so lucky that my mechanic shut the garage down for me and gave my Q his undivided attention when he did the job. I had illustrations and every hose and part were all lined up across the floor. He laughed and laughed at me and just kept saying pass me the next one until it was all done. Having the job done was the easy part, because my mechanic makes everything look easy and never complains. He didn't complain about doing the job at all and found it to be easy and straightforward, but stressful on his back. It was my preparation that killed me. All the part numbers and supersessions drove me mad. If I had to rely on the local dealer to order the parts, I'd still be waiting now for some of the parts.

[peaceofmindinhim]

Hey all,

So here's the update on everything... (lino/qship/paul wall, et al...)

Took car to mechanic friend and did a pressure test. Only leak was coming out of the radiator. No hoses were leaking. Not quite sure why they told me the bypass hose was leaking when we saw nothing. Regardless, applied 13 lbs of pressure and only leak was out of the radiator. I did this several times, to make sure I wasn't being too optimistic.

Then, took the car to a buddy's shop, and did a block test to see if my head gasket was indeed blown. The liquid stayed blue. So no blown head gasket!

Then went to Kragan's, bought a thing of fixing solution for the radiator from Bar's Leak. Put that in my radiator, topped it off with coolant, and let the car idle for 15 minutes, then drove it for awhile. I've pushed it a bit, and had the A/C cranked - and I'm not seeing any leaks when I look under my car.

I haven't pressure tested it again yet...going to give it a few days, but so far, I'm feeling optimistic. That said, I still don't mind replacing the radiator here soon. Just happy it appears I don't have to take apart the plenum. I was starting to have nightmares!

** a few hours later **

have driven the car and let car run while trying to get my 10 disc changer to work...have driven/idled the car for probably an hour or two, still no leaks.