Modified 2002 Q45 Overheating Again

[HollywoodJackson]

Hey everyone, especially all the F50 Q45 OG's we have here. I have an update on the overheating problem that has been haunting my ride.

I just drove to Tucson, AZ again, from L.A. I left at night, so the ambient temp was kind of cool. Took a few naps on the way. I got to Phoenix, just in time for the morning rush hour. And the car ran hot on the freeway in the stop and go action. The temperature gauge was working. When I got to my destination, I went thru the steps of refilling the system.

The last time I drove the Q to Tucson was a total nightmare. It was in August 2018, excruciatingly hot in the desert, and the car kept overheating. I found out, the fan was never operating at more then half speed. I remedied this, by unplugging the sensor at the water pump, defaulting the fan to high speed at all times.

So with the fan at high speed, and with the coolant topped off, I didn't expect any issues driving back to L.A.

Cruising at 100 MPH, and the RPM's at around 4,300... The engine SHUT DOWN! The temperature gauge had a normal reading, which I assume is around 205 degrees. The gauge didn't show sign of overheating. I pulled over, and the car wouldn't start. I think it wouldn't even try to start. After about 15 minutes though, it did fire back up. I drove for another hour or so, and it did the same thing, engine died. I waited for approximately another 15 minutes, and it fired up. After that, I stayed at around 70-80 MPH and was able to drive 3-4 hours straight all the way to L.A. with no issues.

This was a few weeks ago, Since then, I've had to top off the coolant once or twice. Saturday, I drove up the mountains with a few other enthusiasts. After beating on the car, driving in manual mode, high revs, the same thing happened again, ECM cut power to the engine. I had to pull over, and after about 10-15 minutes, it started. This time though, immediately after cutting power, it would turn over, but just not start. Also, the temp gauge showed a normal reading. The coolant overflow was full though. It was hot, but not too hot as to where I couldn't stick my finger in it.

I got to the point where now I'm starting to think the problem is with the flow (or lack of flow) thru the radiator. And maybe the temp sensor at the bottom of the radiator is toast as well. Checking the FSM, makes me think this is where the problem may be. as the temp sensor on the bottom of the radiator controls the fan speed (with the water pump housing sensor plugged in, the fan wouldn't go over half speed).

I'm going to check the fan for flow/stoppage, and replace the temp sensor at the bottom of the radiator, and possibly the thermostat as well. Hopefully this will resolve the overheating this car has been prone too for the last 3 years.

Sidenote, the car revs high, because I swapped in a 350Z differential. Cruising speed of 65 MPH will be around 3,000 RPMs.

Any experience or thoughts would be greatly appreciated (Ed_Bwoy!)

All the best,
~HollywoodJackson~

The codes that were hit when I was on the freeway doing 100 MPH...
P1480 and P1480 Pending
P1720 and P1720 Pending
P0340
P0120

And the codes from this weekend going up the mountain...
P1480 Freeze frame and P1480 Pending
P0340 and P0340 Pending
P1720 and P1720 Pending

On this cheap Innova Scanner, it also says on the screen...
I/M MONITOR STATUS and underneath that there are icons for M, F, CC, C, O, EV, and OH. Also a little 'car' symbol, and an engine with MIL on it. I have no idea what those represent.

[BCC93QT]

I saw edbwoys q45s for sale a few weeks ago on CL. And I'm really regretting not putting in an effort to grab his blue supercharged one. Seems he is set on moving forward on the m56 etc. Not to hijack your thread but it is becoming very difficult to login and post on this site. Very frustrating just to login

[Q451990]

but it is becoming very difficult to login and post on this site. Very frustrating just to login

We recently changed some provider stuff behind the scenes, and are having some transition challenges, but I promise it's being addressed. I know that doesn't make it more fun to use the site, but I wanted to let you know that it's being addressed - rather than the site being neglected.

[EdBwoy]

The electrical connector at the water pump isn't a sensor, that is the solenoid. It is controlled by the ECM, and the operation can be summarized as this:
fully ON signal = slowest fan speed
fully OFF signal = fastest fan speed
So, yeah the fan gets various signals to determine when/at what speed to run, and it is very possible that although it seems slow to you, nothing has triggered it to go full speed when you're looking at it.

Engine speed, vehicle speed and coolant temperature are among these trigger signals.
Now let's look at some of your codes:
P0340. Engine speed - camshaft sensor. That is the biggest contributor to your starting issues. Replace the camshaft sensor with an OEM unit.

P1720. Vehicle speed - weren't you among the members who were having a non-symptomatic speed related code after changing your rear differentials? Not sure what you can do about it if you still have different gears in the back.

P1480. Cooling fan solenoid. Reconnect the connector you unplugged at the water pump and let the computer do its job.
If you still think it's overheating and/or you keep losing coolant, inspect the water pump for failure. It can actually be bad and is leaking or not pumping fluid.
Check the fan too. The fan should be constantly jogging when the car is on, so if it ever stops, even with AC turned on, that's an issue.

Btw, when you say the car is running hot, where is the needle on the gauge?


****
How's that for timing, huh? It's almost like you tagged me, but I just happened to be in the neighborhood to see your post.
Which leads me to BCC's point. Some changes are being made on the websites that NICOclub owns. I know all the changes are being made in good faith and for our benefit, but I am aware that some of us are getting inconvenienced. I do stay logged in, but the forums are almost unusable to me as well.
It is also true that I am stepping away from the M45 and Q45 platforms, but I don't plan to quit cold turkey. I still have a presence on the forums and still offer help where I can, when I can.

[HollywoodJackson]

Hey thanks for the reply Ed_Bwoy.

I read in the FSM that when the AC is on, the fan defaults to high speed. This past summer, when the car kept overheating every 45 minutes while driving it on the freeway, I confirmed that while the AC was on, the phone was turning extremely slow. That's when I remembered, unplugging the fan, also defaulted it to high speed. I did that, and the cars range tripled. Fan is always at high speed, and the car doesn't runs a lot longer. That's why I 'think' there is a problem with the fan speed signal/sensor.

As of late, when the car has been turning itself off, the temp gauge needle stays at normal operating temp, with the needle just above the 9:00 spot on the temp gauge. The needle doesn't go above that. But when the car shuts itself off (fail safe mode I'm guessing) and I open the hood, it appears to be running hot. Coolant is low. Reservoir is full. However, I can stick my finger in the reservoir, and it's not unbearably hot. Can leave my finger in the coolant.

So, it seems, there is one temp for the fluid in the reservoir, and another temp for the coolant in the either the radiator, or the block. It's making me think that the radiator may be clogged up, and the clog has gotten worse. To the point where now the temp sensor on the radiator is getting exposed to hot coolant.

The water pump was replaced, by me, in 2015, with a dealership part. It could be faulty, I'm not sure. I replaced the water pump because the one that was in there was leaking fan fluid, badly.

P0340 - I'm not sure I have a starting issue. The car starts perfectly fine. Except after it runs hot and cuts itself off. I assume this Fail-Safe mode. Otherwise, no starting issues.

P1720 - Yes, vehicle speed sensor. I have the sensors at the diff unplugged. Traction control system disabled, ABD system disabled, 'ci este la vie'! The front wheel sensors are still plugged in so the MPH gauge works. With the diff sensors plugged in, TCS and ABDs systems do work, but the check engine light comes on as the ECU senses a problem with with the RPMS and the speed ratio being out of wack

P1480 - I can plug the solenoid back in. But I'm pretty certain that with the car the way it is now, its going to over heat as the fan won't go over half speed, waiting on a signal from the ECU to instruct it to speed up.

I'm going to pull out the radiator this weekend and check it for good flow. I'll probably try swapping the temp sensor on the radiator as well.

All the best,
~HollywoodJackson~

[EdBwoy]

I read in the FSM that when the AC is on, the fan defaults to high speed.

- Not necessary. It varies based on refrigerant pressure, vehicle speed.

This past summer, when the car kept overheating every 45 minutes while driving it on the freeway,

- Overheating to mean, the needle on the gauge climbed all the way up to H?

I confirmed that while the AC was on, the phone was turning extremely slow.

- As referenced above, the fan could turn as slow/fast as 700 rpm. You'd probably need a strobe light to verify speed, because that could look like slow to one person and very fast to another

As of late, when the car has been turning itself off, the temp gauge needle stays at normal operating temp, with the needle just above the 9:00 spot on the temp gauge.

- Seems like it runs hot to me. My Nissans have been typically a tick below the 9 o'clock or middle mark.

But when the car shuts itself off (fail safe mode I'm guessing) and I open the hood, it appears to be running hot. Coolant is low. Reservoir is full. However, I can stick my finger in the reservoir, and it's not unbearably hot. Can leave my finger in the coolant.

- How do you determine it's running hot when you're under the hood?
- If you can shut off the car and immediately open your radiator cap to verify coolant level in the filler neck (without splashing hot coolant), there is a problem.
- For a fail-safe condition, does the gauge show as max temperature or the center display say "engine over temperature" or a similar message?

So, it seems, there is one temp for the fluid in the reservoir, and another temp for the coolant in the either the radiator, or the block. It's making me think that the radiator may be clogged up, and the clog has gotten worse. To the point where now the temp sensor on the radiator is getting exposed to hot coolant.

- 2 coolant sensors. One at the bottom left of the radiator, and another behind the left cylinder head.

The water pump was replaced, by me, in 2015, with a dealership part. It could be faulty, I'm not sure. I replaced the water pump because the one that was in there was leaking fan fluid, badly.

- Did you replace the thermostat with an OEM part as well?

P0340 - I'm not sure I have a starting issue. The car starts perfectly fine. Except after it runs hot and cuts itself off. I assume this Fail-Safe mode. Otherwise, no starting issues.

- Camshaft sensor issues manifest in different ways (refusing to start, dying at idle, dying on the highway, etc) and sometimes these things happen without a code. for example this
From experience, once the code appears, disregarding it would be a slap in the face of advancements in OBD2 diagnostics.

[Q451990]

If you aren't using something like Torque Lite with a Bluetooth dongle, I would consider getting that. You can get actual coolant temperature numbers, instead of trying of the dash temperature gauge. Most dash gauges have a dead band in the middle to avoid alarming the driver. By the time it's noticeable on the gauge, the engine temperature has been rising for a while.

[HollywoodJackson]

- Overheating to mean, the needle on the gauge climbed all the way up to H?

Yes, last summer when the car overheated, the temp needle would climb almost to the top.

- As referenced above, the fan could turn as slow/fast as 700 rpm. You'd probably need a strobe light to verify speed, because that could look like slow to one person and very fast to another

Does the fan have more than two speed settings? When the fan solenoid was plugged in, it would be at half speed, (unless if the FSM is incorrect about the fan having two speeds). I had to take the air intake off (above the radiator) to look and see if the fan was moving at all. And it was. Once I unplugged the solenoid, you can hear the air blowing with the hood closed. Unmistakably faster. No doubt about that.

- Seems like it runs hot to me. My Nissans have been typically a tick below the 9 o'clock or middle mark.

I can't debate that. Since I've owned the car, the needle seemed to always been at just a tick over the 9:00 mark. It could have always been running slightly on the hot side too.

- How do you determine it's running hot when you're under the hood?
- If you can shut off the car and immediately open your radiator cap to verify coolant level in the filler neck (without splashing hot coolant), there is a problem.
- For a fail-safe condition, does the gauge show as max temperature or the center display say "engine over temperature" or a similar message?

The shut off issue just started. I assume it's related to engine/coolant temp, as it will only start again after approximately 10-15 minutes. I won't open the radiator cap immediately after shutting the car off, or after it shuts itself off. I'm assuming its running hot.

- Did you replace the thermostat with an OEM part as well?

I have replaced the thermostat with an OEM from Infiniti

- From experience, once the code appears, disregarding it would be a slap in the face of advancements in OBD2 diagnostics.

I can understand that. I'm thinking if I put the OEM diff back in, plug the diff sensors back in, plug the fan solenoid back in, etc... None of those other codes will pop up. But the overheating will remain.

I'm starting to accept the reality that, I'm going to have to do the head gaskets.

If you aren't using something like Torque Lite with a Bluetooth dongle, I would consider getting that.

I would like to grab a bluetooth dongle. Does anyone have a link to a good one on Ebay?

Thanks everyone, especially Ed_Bwoy for any input. It's definitely appreciated. I want to get this overheating issue resolved finally. Ed_Bwoy, how difficult on a scale of 1-10 would you consider the head gasket job (with the engine remaining in the engine remaining inside the bay?

All the best,
~HollywoodJackson~

[HollywoodJackson]

- Seems like it runs hot to me. My Nissans have been typically a tick below the 9 o'clock or middle mark.

You were correct. My temp needle is normal at just below 9:00, not above it. I had that part mixed up.

What is the part of the engine that the 'cooling fan pump / water pump' is bolted to? I may have stripped one of the bolts/holes there when I changed the water pump. Specifically, the one bolt/hole at the very bottom.

All the best,
~HollywoodJackson~

[EdBwoy]

It seems like you handled your overheating issues already. Maybe I got mixed up, but I don't see any indication of current overheating in what you have posted.
Maybe a leakdown test kit from a parts store will shine a little more light to it.
To answer the head and head gasket job - yes, you can do it with the engine still installed. May he RIP; Dean told me he got this job done and put the car back together: 2004-q-head-removal-t587376.html

From my 03 Q45 FSM, I see that the fan has various speeds and not a just a min/max. I also see that the engine speed is a determinant of fan behavior. As I mentioned, you might really have overheating issues, but you definitely have a camshaft sensor (engine speed) issue.
Replacing the cam sensor is easier than about any other troubleshooting step you could take. Is there a reason you don't want to look at that possibility?

[

But yes, you have a coolant leak somewhere. You shouldn't need to keep adding coolant. Remove your engine plastics and look around the engine bay. A cracked radiator wouldn't be out of the question.

[98_Q45]

I fixed a possible head gasket leak with some K-Seal. The tiny little blue bottle. That’s been since December, and I haven’t lost hardly any coolant since using it.

Also 100 mph is not cruising speed! Slow the f*** down lol. I find my Q rides best between 70 and 80 mph. 90 feels nice for a few minutes, but it seems hard to “hold” anything beyond 75 without it feeling like I’m burning thru oil and gas.

Sometimes I get tired of people people passing me on the highway. Why can everyone else go 90 mph, yet I go the speed limit and get pulled over and searched And sometimes I do push 115 mph if I feel like I need a rush of adrenaline. But for the most part, I like to save my gas money especially when I’m pushing 1,000/2,000 mile road trips every monthX

[HollywoodJackson]

It seems like you handled your overheating issues already. Maybe I got mixed up, but I don't see any indication of current overheating in what you have posted...
Maybe a leakdown test kit from a parts store will shine a little more light to it.
To answer the head and head gasket job - yes, you can do it with the engine still installed. May he RIP; Dean told me he got this job done and put the car back together: 2004-q-head-removal-t587376.html

... Replacing the cam sensor is easier than about any other troubleshooting step you could take. Is there a reason you don't want to look at that possibility?

... But yes, you have a coolant leak somewhere. You shouldn't need to keep adding coolant. Remove your engine plastics and look around the engine bay. A cracked radiator wouldn't be out of the question.

I know I haven't fixed the overheating issue. I've just applied a bandaid of sorts. Specifically, when I unplugged the fan pump solenoid and it forced the fan to blow at high speed all the time. And since the past several days, something else has developed. Codes keep popping up, P1480, P1720, and P1772. The first, being the fan pump solenoid. So I've plugged that back in. The three codes stopped popping up so far. I did flush the heck out of the system about two weeks ago. I will be keeping my eye on everything, to see what's going on.

I don't mind replacing the cam shaft sensors. I'm starting to believe I either have a coolant leak under the plenum, or a cracked head gasket.

Also 100 mph is not cruising speed! Slow the f*** down lol. I find my Q rides best between 70 and 80 mph. 90 feels nice for a few minutes, but it seems hard to “hold” anything beyond 75...

I had a Y33. This F50 I have now though, is sitting on racing coil overs. They feel stupid, bumpy and stiff, until the car gets up to around 85 MPH, at which point they start to feel at home. Other than the overheating issue I've had with the car... It eats highway and has a voracious appetite for it.

All the best,
~HollywoodJackson~

[HollywoodJackson]

May he RIP; Dean...

Sorry to hear about Dean, RIP.

[ZiprHead]

If you aren't using something like Torque Lite with a Bluetooth dongle, I would consider getting that. You can get actual coolant temperature numbers, instead of trying of the dash temperature gauge. Most dash gauges have a dead band in the middle to avoid alarming the driver. By the time it's noticeable on the gauge, the engine temperature has been rising for a while.

I second this. Get the actual reading using this tool.

And if you want to spend a few bucks for the full Torque app, you get some pretty cool features with it.

[HollywoodJackson]

Blown head gasket, and a loud tapping noise now. I have a compression tester, and a stethoscope. Loud tapping, bigs down easily at operating temp. Worst case scenario, engine swapping this weekend for another VK45DE. Get this one out and address it’s issues, clean it up nice, spec of paint maybe some powder coating, and then reinstall it.

What ever happened to the user that was rebuilding his VK45 with modified internals?

All the best,
~HollywoodJackson~