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Discussion Starter · #1 · (Edited)
I bought a cruze at auction, that was lightly hit in the front. It had some engine codes, one was related to the upper purge solenoid, which was replaced. The thermostat was cracked and that was replaced.
After we filled it the first time, we found that the water pump was leaking. So that was replaced. It seemed to be OK then started overheating again, but would just do it after about 20min of driving, then be fine after that. A different mechanic did a compression test on the cooling system and found a crack in the upper cooling line dischage pipe (another plastic), so that was replaced.
But, the mechanic put full strength dexcool in, instead of mixing it. He said it was no biggie.
Now i'm getting a P0420 code while driving. I noticed the engine temp gauge is barely over 1/4 most of the time. I'm seen other posts mention the gauge normally sits just below 1/2 normally (is this correct?) Could the engine be running too cool, or the full strength coolant causing misreads of temp causing exhaust mixture /catalyst issues? I can clear the code, and drive for a while. It kinds comes back randomly.

Also, I'm getting a P0300 code in the mornings with rough idle. On my scanner, I can get into the ECM and show misfires, and there are none. If I clear the code, the engine idles normal. Is that weird?
Why does this code also cause about 10 other codes in ABS, Stbil, HVAC, SRS, etc. Seems dumb.
So, on this one I'm leaning towards that valve cover crack I havent seen yet (caused by accident). Would the valve cover also cause p0420?

GEN1, 1.4L, 2014 LT
 

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I bought a cruze at auction, that was lightly hit in the front. It had some engine codes, one was related to the upper purge solenoid, which was replaced. The thermostat was cracked and that was replaced.
After we filled it the first time, we found that the water pump was leaking. So that was replaced. It seemed to be OK then started overheating again, but would just do it after about 20min of driving, then be fine after that. A different mechanic did a compression test on the cooling system and found a crack in the upper cooling line dischage pipe (another plastic), so that was replaced.
But, the mechanic put full strength dexcool in, instead of mixing it. He said it was no biggie.
Now i'm getting a P0420 code while driving. I noticed the engine temp gauge is barely over 1/4 most of the time. I'm seen other posts mention the gauge normally sits just below 1/2 normally (is this correct?) Could the engine be running too cool, or the full strength coolant causing misreads of temp causing exhaust mixture /catalyst issues? I can clear the code, and drive for a while. It kinds comes back randomly.

Also, I'm getting a P0300 code in the mornings with rough idle. On my scanner, I can get into the ECM and show misfires, and there are none. If I clear the code, the engine idles normal. Is that weird?
Why does this code also cause about 10 other codes in ABS, Stbil, HVAC, SRS, etc. Seems dumb.
So, on this one I'm leaning towards that valve cover crack I havent seen yet (caused by accident). Would the valve cover also cause p0420?
Year and model of cruze?

Helps the real mechanics on here to try and give you a good answer
 

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Discussion Starter · #4 ·
Some more info, would really appreciate some advice!

COOLING - Can someone please let me know what the normal Radiator and Engine temps should be, and where the dash gauge usually is? I understand these small motors don't generate much heat, but my temp gauge (verified working with scanner) barely gets to 1/4 most of the time (after a 20 mile drive, 13 miles on Interstate at 65). Other posts I read I though it normally hangs out just below half? I've gotten the gauge to about 1/2 after letting it idle for about 20min and then when I start driving, the goes back to 1/4. I'm wondering if these wild temp swings are being caused by coolant mix (probably 85/15).

MISFIRE - P0300 - Only getting this in the morning at startup. I plugged in my scanner before I started the car this morning. I recorded 2 misfires on cyl1 and 634 on 3 (engine shuddering), then it stopped and cleared up in under a minute. I cleared the codes and counts, drove 20 miles, and only recorded 2 misfires on 2 cyl the whole trip. One mechanic told me "its always the coil pack". Is that true?
What causes the misfires only in the morning? I am leaning towards a coolant leak into the cyl just based on the valve and head gaskets used on this motor commented in this forum. I'm not seeing any white smoke at start, but do get a faint coolant smell.

P0420 - I got this code on the drive also. Do these cats wear out at 60K miles? Or is it at all possible related to lack of engine heat up? Or another cause.

I don't want to throw money at a coil pack and a cat without success (I've read people doing that on this forum without success). I haven't found or heard any obvious vacuum leaks, I've read that is common (PCV test covering the hole OK).
 

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At normal operating temperature the gauge should be one dash below the 1/2 mark. Did you replace the thermostat with a GM part or aftermarket?

For the misfire, remove the coil pack and remove the rubber boots. There are little springs in there that corrode sometimes that can cause random misfires.

And for the P0420 code, I also have a 2014 model and had my converter replaced at 75k for the same code so it is possible.
 

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Discussion Starter · #6 ·
thanks eagles121.
Yes the thermostat was delco part.
When I removed the coil pack, what I saw was a small ring of orange coolant in the chamber where the plug is. I removed the plug (#2, the one that is misfiring and happens to be this one) and it looks like a pool of liquid in there too. So I'm leaning towards head gasket now..
Would this issue , if true, also cause the P0420?
 

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Back up the bus......you are overcooking this.
I suspect after the overheat moments that occured after the thermostat change may have damaged the new stat......most likely now in 'fail safe' meaning it is partially open at all times.
The mechanic'?' that said a high concentration of dex cool is harmless is absolutely incorrect.......cooling efficiency, the ability of the coolant to transfer heat to the radiator tubes, decreases above 60% dex cool.
The current concentration would actually make it run hotter, but again, I think the present thermostat is masking this.

For now, concentrate on the above......yes, codes are set if running too cool.
Whatever you saw on the plug bases is.......I don't know......if it was coolant the head would be cracked to get coolant over there. Rather unlikely.

Don't worry about the cat code till the cooling thing is resolved........baby steps.

Rob
 

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Discussion Starter · #8 · (Edited)
can/will the thermostat get itself out of failsafe? Like unplug the battery for a day or something? I don't wanna buy a new stat if it can be reset. But if as you say it's "damaged" then maybe not.

That may be part of the problem but still got misfire on cyl2, where I saw the fluid. We were looking at it at the shop last nite, and we all agreed when revving it we do see some white smoke.
 

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Discussion Starter · #9 ·
Back up the bus......you are overcooking this.

Whatever you saw on the plug bases is.......I don't know......if it was coolant the head would be cracked to get coolant over there. Rather unlikely.

Rob
I'm guessing that a little bit of coolant was boiling up through the plug, there is a video of this on youtube in a cruze somewhere.

Oddly, when I put everything back together from investigating the plugs, it hasn't thrown a p0300 yet, but now threw P2181 (cooling perf), that one is new since all the other cooling parts replacements.
 

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I'm guessing that a little bit of coolant was boiling up through the plug, there is a video of this on youtube in a cruze somewhere.

Oddly, when I put everything back together from investigating the plugs, it hasn't thrown a p0300 yet, but now threw P2181 (cooling perf), that one is new since all the other cooling parts replacements.
That P2181 is telling you the coolant is not reaching operating temperature......this results in a over rich condition (ecm responding to coolant temp information).

Also, this stack of codes is confusing and often related to a high resistance condition of the battery ground cable.....this cable has had its warranty extended to ten years due to a high rate of failure......has yours been replaced?

The P0420 can be triggered by a over rich condition but the cat might be dieing because of continued rich operation.
It may clean up once the mixture is back under control. The code sets when the pre cat O2 and post cat O2 don't see enough difference.
On a reader, the pre cat will make dramatic voltage changes as it works to adjust the fuel mixture, always looking for that perfect mix.....with a working cat, the post O2 will show very slow gentle voltage rises and falls........that is how the system knows the cat is functioning.

Rob
 

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Diagnose your P300. That is a random misfire. You need to figure out if you have bad ignition parts or a compression problem. If the car overheated bad enough most likely you have a warped head or blown head gasket. You need to do a compression check and figure out if you have good compression across all 4 cylinders. Before throwing coil packs, plugs etc at it, take a 1/2 hour and do a compression check. It is easy and will tell you if there is any engine problems.

I then would move to figuring out why it is running rich before it kills your cat.
 

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Chiming in here to answer the normal operating temp question; it's 221 degrees F is 'normal operating temperature' of your engine. That also is what your thermostat should be. You didn't mistakenly get a 160 or 180 did you?
 

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Discussion Starter · #14 ·
Chiming in here to answer the normal operating temp question; it's 221 degrees F is 'normal operating temperature' of your engine. That also is what your thermostat should be. You didn't mistakenly get a 160 or 180 did you?
I bought it from the dealer, for a 1.4L. If there are different Delco parts they didn't tell me. It was part # 55593034
 

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Discussion Starter · #15 · (Edited)
Also, this stack of codes is confusing and often related to a high resistance condition of the battery ground cable.....this cable has had its warranty extended to ten years due to a high rate of failure......has yours been replaced?


Rob
I'm not counting on the dealer to do anything for me since it is salvage. How does one test this? Unhook the cable and test on meter? What resistance is good/bad?
From what I read of the service pdf, it says Radio, lights flicker, power steering etc issues, which I don't seem to have.
 

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If you have a negative battery cable issue, your infotainment will turn on and off repeatedly. When that happens your blue tooth disconnects, radio will stop, and you won't hear your blinker sound since that comes through the audio speakers. Until of course it all comes back on, which takes about 15 seconds in my experience.
 

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I'm not counting on the dealer to do anything for me since it is salvage. How does one test this? Unhook the cable and test on meter? What resistance is good/bad?
From what I read of the service pdf, it says Radio, lights flicker, power steering etc issues, which I don't seem to have.
A good cable will show essentially zero resistance.

Rob
 

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Discussion Starter · #18 · (Edited)
Pretty much where I'm at now is...
I haven't had a misfire code since I took the plugs out and put them back in? #2 was loose maybe? I get a little shaking when I start the car cold but nothing that does the freak out P0300 with the ABS/Track services warnings.
Did compression test, no issues found.
Flushed the coolant, and replaced with 50/50 Dexcool. Engine still barely gets above the second tick on the gauge.
Interestingly after we did this, very shortly it popped a P0598 code (haven't had this one yet), which means the thermostat is bad. This was suspected anyway based on previous info. The dealer exchanged it since I've only had this new one for about a month... will be putting that in tomorrow.
STILL have the P0420 code. Kinda hoping that will go away when the engine runs at normal temps...
I don't have any of the power issues mentioned.

**UPDATE
So we went to put the new thermostat in, and what we found is it HAS no thermostat. Holy heck did the one the dealer sold me originally not have the thermostat in it, just the housing? Mechanic that put it in swears it was but they don't just disappear. Beyond the fact it should have thrown an P0598 a lot sooner I would think, right. What a mess...
 

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Discussion Starter · #19 ·
Back to square 1.
With the thermostat apparently working/present again, I'm back to codes P00B7 (coolant flow) and P0598 (thermostat). I get the "A/C off" (not even running the A/C), the the "Idle now", so I pull over, wait 2 min, and then its back to normal. Only happens at interstate speeds. I took a video.
Since the water pump has already been replaced, i dunno what to do. I don't know how a "flow" issue is measured in the coolant system. All the hoses look good. I can't find any leaks.
And P0420 still lingers as well.
I liked it better when the thermostat wasn't there... :)
 

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Discussion Starter · #20 ·
I thought my mechanic did a compression test, but actually did a leak down test. I ended up taking it to the dealer and they did a block test and determined the head is bad and coolant leaking into exhaust. So, just bought a whole new motor with 15k on it , which is cheaper and easier than the head IMO. GTG.
 
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