GM Volt Forum banner
1 - 14 of 14 Posts

· Registered
Joined
·
23 Posts
Discussion Starter · #1 ·
2017 Chevy Volt Premier, 153K miles.
I got the P0401 fault code last week so did the EGR valve cleaning and cleared the code.
This morning the weather was cold at about 18F.
Preconditioned, hopped in and drove in Hold to warm up the engine.
About 25 min into my drive I got an 'engine overheating' and 'pull over' error on the display.
When I pulled onto the shoulder it was steaming antifreeze. The coolant temp was right around 200F.
I let it cool down and then drove back home. But, the last 10 miles were on ICE power.
Check engine light came on and I had to stop due to overheating every ~2 miles.
The coolant went up to 230-240F.
So, the car sits on the driveway with evidence of coolant over the engine compartment.
I thought it might have been the coolant hose I removed from the EGR valve.
But, that was one of the few things that was dry.
I have not investigated in detail yet.
But the coolant leak definitely appears to originate on the passenger-front area of the engine bay.

I did run Torque Pro and got the following codes. Once this happened the engine went from smooth running to definitely rough. So, not surprising I get a knock sensor code.

Any ideas? Logic leads me to point to the EGR Valve cleaning. But, I don't think this is a situation where I reinstalled something incorrectly (not my first rodeo wrenching under a hood). The temp definitely went very high at ~240F but I stopped each time immediately so I feel I was able to limp home without internal damage.

I have the upcoming Thanksgiving weekend to do some wrenching on this car. I am leaning on replacing the EGR Valve (and possibly the cooler too). I am not sure on parts availability at present.

Let me know any other ideas!

Paul.
---------------------------------------
Vehicle VIN: 1G1RB6S51HU103213
Vehicle Manufacturer: Chevrolet
Vehicle Calibration ID: Not present

Current Fault Log
------------------
P0325: Knock Sensor 1 Circuit (Bank 1 or Single Sensor)
P0AC4: Unknown code - More information may be available on the web
P16E0: Unknown code - More information may be available on the web

Pending Fault Log
------------------
P00B7: Unknown code - More information may be available on the web
P0324: Knock Control System Error

Historic Fault Log
------------------
ECU reports no historic faults
Other discovered fault codes
(possibly pending, current or manufacturer specific)
----------------------------------------------------
ECU reports no other fault codes logged

End of report.
 

· Registered
Joined
·
23 Posts
Discussion Starter · #5 ·
When the EGR valve fails, the "non walk home" fuse fails. One of the things on that fuse is the electric thermostat for the engine, so the engine will overheat if that fuse is blown.
No idea about the coolant leak. Hopefully, not a warped head or bad head gasket due to overheating.
I always thought when the F3 fuse blew the car would not operate. I'll definitely take a look!
 

· Registered
Joined
·
23 Posts
Discussion Starter · #7 ·
I have a parallel thread going on FB Chevy Volt Owner group as well......

The F03 fuse wasn't blown. After cleaning the valve I had cleared the P0401 code. Then, I got the new codes shown above when the car overheated and ran very rough. Do you still think this is related to the EGR valve/cooler? Or could this be something else? FYI, while I cannot find the source of the coolant spray pattern under the hood the reservoir tanks still look at normal levels. So, it may simply have been a pressure release. The coolant is more prevalent in the vicinity of the EGR valve though. If the cooling system releases pressure what region under the hood would it most likely be concentrated?
Also, once confirming the F03 fuse was OK I briefly ran the vehicle with the hood open for a brief moment with the EGR connected and then disconnected. In that brief trial, I saw no difference and the car seemed to idle well without any knocking. I guess the next step is to run the engine until the car gets up to temp and see what happens.
 

· Registered
Joined
·
23 Posts
Discussion Starter · #9 · (Edited)
coolant release would be from the reservoir pressure cap which likely has a nipple and hose leading away and usually pointed downwards away from the engine.
UPDATE: I finally noticed that the gasket did slip while I was reinstalling the EGR valve. It was hanging from one bolt and not seated properly. I removed the valve and reinstalled correctly.... well, almost. One of the bolts has fallen into the abyss. I can't find it. Anyone know the EGR valve mounting bolt size? (UPDATE: I found via a google search it appears to be M8-1.25x33.4mm. I'll see what I can find locally tomorrow. UPDATE #2: Google was wrong... M6-1.00x33mm is the correct bolt size for future reference).

I ran the engine with the hood up until it was up to full temp. No discharge from reservoir. But, coolant smell and vapors from around the EGR valve. I have a valve, cooler, and gaskets on order. I found someone selling new OEM valves on ebay. I am getting the cooler and gaskets from an online Chevy dealer/parts vendor. I am hoping the valve I receive will be OK. So, this Thanksgiving weekend I will remove the catalytic converter and get it ready for the new parts. Interestingly, the P0401 code has not returned. Engine coolant temp go to 210F. I think the spray occurs when it really gets higher... 220+. I didn't want to go there again! Overall, the engine ran smoothly for the most part. A couple brief stumbles/knocks. The knock sensor fault codes are still present. I am hoping that is a byproduct of the EGR components being faulty.
 

· Registered
Joined
·
23 Posts
Discussion Starter · #12 ·
Sadly, I fixed the exhaust leak but I still get overheating. I took the car for a test drive after letting the engine warm up in my driveway. It went to 240F+ fairly shortly. I still have the P0324. P0325, P00B7 codes. Still no return of the P0401. F03 fuse still good. I will await the new EGR parts but could this be my thermostat? P00B7 is a low coolant flow code. And, I am getting high coolant temps. Maybe it is the thermostat??
 

· Registered
Joined
·
23 Posts
Discussion Starter · #17 ·
That's kind of strange... Why didn't he just unplug the EGR connector and install a new fuse? That'd be the same non-functional EGR valve, but all other stuff'd be functional.
The fuse wasn't blown. Has never blown. I had the EGR unplugged on my driveway and the engine still approached overheating with the engine idling for 30 minutes. Even though I did the valve cleaning procedure I decided to do a proper replacement. My Volt carries me on a 125-130 mile daily round-trip commute for work. I want to ensure I have it fixed optimally.

I'm due for an engine coolant flush/refresh so am going to do a thermostat swap while I am doing the EGR work. Parts cost isn't excessive and I feel it is a wise move while I am doing the work. I have another vehicle so I can keep the Volt offline while I am awaiting the EGR parts.

Latest theory.... when the EGR valve gasket slipped off 2 of the 3 bolts and was hanging from a single bolt this resulted in an incomplete seal and an exhaust leak, particularly once up to highway operating temps. There is a second smaller passage from the engine to the EGR valve. I assume it is a coolant passage as the valve has a coolant hose going to the small barbed pipe... I figure coolant needs an in-and-out pathway. So, this could have allowed air to enter the cooling system and some coolant loss that was not detected initially. The reason I am thinking this may be a possibility is that when I jacked the front end up to remove the cat converter the coolant reservoir appears to have dropped to about the 25% level. I wonder if angling the car was enough to 'burp' the system and drop the reservoir level. I'm grasping at straws but I thought I'd run that by the group.

That darn EGR valve gasket getting dislodged on installation was almost invisible on inspection! Shadows and engine grime (and less the perfect vision!) made it hard to spot, even with a strong flashlight!
 

· Registered
Joined
·
23 Posts
Discussion Starter · #21 ·
Update: I replaced the EGR valve, cooler, and thermostat with OEM GM parts. I had to add an entire gallon of Dexcool coolant which surprised me. Everything worked great on about 40 miles of test driving. Drove to work this morning, a 62-mile highway commute. All seemed good. Coolant temps were 185-215 but predominantly around 195F. I did note a faint scent of coolant from the vents but attributed that to a residual amount in the engine compartment. Well, on the way home the engine temp shot up to 255F+. I knew something was up as the heater was running cold. I had thrown another jug of Dexcool in the trunk so after cooling for a bit I topped off the coolant. The car ran in ICE mode but roughly. It then went into 'engine unavailable' and 'reduced propulsion mode. And, the coolant temps went up again. I limped off the highway and pulled into a Chevy dealer service lot. They were already closed. The coolant level was again low. I added more and decided to run the engine in maintenance mode (hood up). The car billowed white exhaust! 🙁 Looks like I will need a new head gasket. The initial overheating from having the misaligned EGR valve gasket likely led to a head gasket failure. It didn't seem as if the EGR gasket would allow that much coolant loss. But, given I had to add an entire gallon of coolant once I finished the repairs I feel the car ran low on coolant, and heated up. blowing the head gasket. My hope is that there is no further damage than a head gasket. I'll let the dealer (who I don't know at all) do a diagnostic. I'll ask them to charge up the EV battery so I can get it home in EV mode. More to follow.
 

· Registered
Joined
·
23 Posts
Discussion Starter · #22 ·
Well, today I had some time and used GDS2 to run the compression test on my Volt engine. Here are my readings:

Cyl #1: 140
Cyl #2: 125
Cyl #3: 118
Cyl #4: 138

Also, the oil on the dipstick was not frothy or chocolate in color. But, the level was far above the full line. I do my own oil changes and a couple months ago when I changed the oil it was spot on the full mark. So, something is going into my oil. Given I am losing coolant my assumption is that the increased oil volume may be a mix of oil and coolant.

Does anyone know what the specs are for cylinder compression?
 

· Registered
Joined
·
23 Posts
Discussion Starter · #24 ·
That doesn't look too bad, maybe a bit of worry with the variation. Drain the oil and see what comes out. The definitive check is to use Block Check type tester to look for combustion gases in the coolant.
I have the combustion leak kit and that is my goal for today. I was hoping to not have to run the engine as it runs very rough and has a noticeable knock. The cylinder variation is what had me concerned too.

If this is a blown head gasket I can repair it. But, I am trying to get the strongest evidence prior to ripping into that level of a project.
 

· Registered
Joined
·
23 Posts
Discussion Starter · #26 ·
Try running the block check without running the engine. Sometimes there is enough gas in the coolant that it will change even with out running. Not definitive - if it passes, you will want to run it again with the engine running. You likely have enough fluid to do it plenty of times anyway...
I ran the engine for about 10 seconds. It actually sounded better than I assumed it would.

The blue fluid in the clear test cylinder bubbled and turned yellow within seconds! No need for the suction bulb to draw in subtle vapors! At this point, I clearly have enough info to tear out the cylinder head and take a look. Hoping for only a blown head gasket and not a warped head and/or cracked head. More to follow.
 

· Registered
Joined
·
23 Posts
Discussion Starter · #27 ·
Update: I am slowly getting to the point where I will be removing the cylinder head. One thing I need help with is the passenger upper engine mount. Once I remove it (to gain access to the timing chain cover) the bolts are single-use TTY. And, when I search on the various GM parts sites they show the mount but I cannot find the bolts listed. Does anyone know the size of the bolts for the motor mount? there are 5 that attach from above. Also, as long as I am asking I will need the bolt size or part number for the engine mount bracket as well

I have the service manual as a pdf but it doesn't show part #s. There must be a GM/Chevy document out there that lists all parts, sizes, and part #s. If anyone has access to such a document I sure could use it right now!
 

· Registered
Joined
·
23 Posts
Discussion Starter · #29 ·
Online parts store typically have exploded parts diagrams with part numbers.
Unfortunately, none of them show the bolts as part of the parts diagrams. And, looking them up via various part names has not been successful. I wanted to get them ordered online in preparation for the coming weeks. But, I'll probably have to stop by a chevy dealer parts counter and see if they can help. In the meantime if anyone else has these details please provide them here. Either for me or someone else in the future.
 
1 - 14 of 14 Posts
Top