Hey all, probably my first forum post ever but I've benefited a lot from people's experience in forums and have some info to share that might be helpful for others. Latter is mainly related to cylinder head replacement and the M32 manual transmission but some other tips also. Sorry if it's a rambling hodgepodge.
Bought a beautiful 2012 sonic LT with 1.4 engine for my 16yr old daughter. Had one lady owner, full dealer service history and was immaculate. Got it pretty cheap because it had a bad ABS issue when I bought it where it would pull hard to the right under braking. They had replaced all the wheel sensors but it turned out to be a bad wheel bearing which has the tone ring embedded in the seal. Someone had tried to remove the driveshaft by prying it out with a screwdriver and mangled the seal. They also had removed the axle shaft by yanking on it which broke the retaining clip on the inner CV joint which then penetrated the boot and caused a leak. Same geek also got happy with his screwdriver when disconnecting the bottom ball joints and damaged the boot on both sides. These are the easiest of all ball joints to remove with no force needed so not sure what they were thinking.
Heads-up - When replacing the wheel bearing, make sure to install it with the tone ring on the inside. I didn't have this issue but I see a lot of posts where it was installed backwards.
Car worked great for about six months though it did have a pretty obnoxious transmission whine that increased under speed. It was under warranty and I took it in to a dealer but two techs and the service manager claimed to have driven it around and could not reproduce the noise.... Could they all have been deaf? apparently.
One day my kid was driving home and the engine over temp light came on. Tried adding coolant to get it home but it was clear the head gasket had blown. The root cause was the thermostat housing had broken internally causing the seal to fail and coolant to leak out. On removing it, I also found the spring and clip that holds the metal disc in place was broken.
Looking around, I could see that I needed to pull the timing cover which in turn meant I had to pull the oil pan before I could remove the head. Since it was turning into a prolonged agony repair, I decided to go the whole hog and fix the transmission bearings also. It's my kid's car and somehow my labor appears to be free so why not. I removed the bumper and radiator pack to make the job easier. It was actually quite fun.
Upon removing my head, it looked like I had a small crack where one of the cylinder head bolts comes through. Given how much labor was involved, I didn't want to risk using it again so bought a refurbished head from here.
HEADSONLY | eBay Stores
It was great quality and worked fantastic but...... they had resurfaced it which according to GM is a big no-no. Why? Well, I used it but later discovered that it resulted in the top surface of the head sitting a little lower then the front timing cover so there was a small step there that resulted in a oil leak when the valve cover was installed. No big, and easily corrected with a small smooge of black silicone. Had I thought it through a little more before installing the head though, I would have bought a shim to correct the installed height from here
Innovative Machine & Supply - Cylinder Head Shims
The other thing to share is on tightening the cylinder head bolts. Some advice says to oil the threads and head of the bolts, while other advice says not to. I played the middle ground and just used a leedle WD40.... Heads-up, you do absolutely need to lubricate under the bolt head and the threads. I will use a graphite grease myself next time out. Why? Because on the last two 90deg turns in the tightening sequence, I was dealing with harsh noises that sounded like the creakiest garden gate of all time from a horror movie. Was freaking scary but I did get them tightened and it all worked out.
As for the transmission, I was lucky in that this car already had the newer style end case that provided more lubrication to the bearings. On dismantling it, I found that every single bearing in the transmission was pitted. The worst was the large lower mainshaft bearing that goes into the front housing by the differential. It was in very bad shape. This bearing would have been running in oil even if the low oil fill was an issue so..... did it fail because the regular GM transmission fluid overheats and fails? Or did all of them fail because any one bearing was shedding metal particles in the oil? I have no idea. When I completed my build, I used Redline MT90 oil which works great except the shifts are a bit notchy on real cold days until the trans warms up a little. My case temperature after a long drive is about 140F now.
For bearings, I got them and a bunch of different size shims from here
https://www.courtenaysport.co.uk/Popular-Items/M32-One-Stop-Gearbox-Shop/M32-Bearing-Kit-Late
This specific link is for the later type end housing so you need a different kit if you have the earlier style. Don't know what that means? Peruse the site and you'll figure it out. They have lots of good information there.
But..... that bearing kit comes with two identical Chinese NGBC front case bearings for the top and bottom mainshafts. One of these is wrong because the lower mainshaft has a trust bearing that runs on the back surface of the supplied taper bearing. The back surface of the NGBC bearing isn't big enough. To fix it, you need the correct *** bearing and the following link is for the latest version (#3) of this bearing. You only need 1ea, but I got 2ea because I had some concerns about the quality of the NGBC bearings.
https://www.ebay.com/itm/2-x-Fiat-55181940-M32-***-INA-Gearbox-Bearing-Replaces-Timken-NP238750-NP929800/173336252791?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
After installing all the bearings, it was time to shim the end case. For this operation, I didn't fully seat the three cups for the end case bearings. I pressed them in about 1/4" shy of the full seated position. I then installed the end case on to the front case with just five bolts and tightened them slowly while knocking on the cover by each bearing with a plastic mallet. When the bolts were fully tightened, I knocked on them all again and then verified that I could easily turn the input shaft through all gears by hand which I could. I also verified there was no apparent shaft play.
Then I measured under the bearing cups with feeler gauges to determine what size shims I needed. I them pulled the cups, installed the shims then put the cups back in. Next I reinstalled the cover with just a few bolts and verified that I could still easily turn the input shaft though all gears and there was no apparent play.
Lastly, I pulled the cover, cleaned the gasket surfaces and used a Permatex Anerobic sealant before reinstalling it. This sealant doesn't affect the bearing shimming by spacing out the cover, and excess sealant that is exposed to air will not harden. That's good on the inside because any smooge that breaks away will get absorbed by the oil and not block oil ways.
On initial startup, I was majorly concerned about how hot the engine was getting without the cooling fan running so spent quite a bit of time troubleshooting that same fan only to eventually find nothing was wrong. Turns out these engines run a lot hotter than the good old days and the fan doesn't turn on high speed until 230F. In normal operation, I might occasionally hit 230F briefly during driving after a cold start but it settles down to around 226F on light driving. The ECM does vary the temperature though so other times I'll average around 205F though I haven't figured out the logic.
It's all built back up and driving absolutely beautifully. Engine sounds sweet and FYI, I did also do the check valve modification to the intake manifold because I found the small rubber disc floating around inside when cleaning the throttle body. My last battle is a small oil leak that is dripping on to the exhaust manifold and having trouble finding the source. I replaced the O rings on the dipstick just this morning so hopefully that takes care of it.
Love, love, love this little car and my kid does also. I can tell it's going to be a bit demanding on the maintenance side but that's all good and having gone thought it as much as I have, I am confident that it is totally safe and reliable for her to drive.
The overall experience did nothing to negate my long standing negative impression of your average auto technician as I fixed a lot of their handiwork along the way. I know however that there are good and bad so wish everyone luck that they find a good one. I myself will keep fixing my own stuff even though I'm getting a bit too old for it.
Take care!
Bought a beautiful 2012 sonic LT with 1.4 engine for my 16yr old daughter. Had one lady owner, full dealer service history and was immaculate. Got it pretty cheap because it had a bad ABS issue when I bought it where it would pull hard to the right under braking. They had replaced all the wheel sensors but it turned out to be a bad wheel bearing which has the tone ring embedded in the seal. Someone had tried to remove the driveshaft by prying it out with a screwdriver and mangled the seal. They also had removed the axle shaft by yanking on it which broke the retaining clip on the inner CV joint which then penetrated the boot and caused a leak. Same geek also got happy with his screwdriver when disconnecting the bottom ball joints and damaged the boot on both sides. These are the easiest of all ball joints to remove with no force needed so not sure what they were thinking.
Heads-up - When replacing the wheel bearing, make sure to install it with the tone ring on the inside. I didn't have this issue but I see a lot of posts where it was installed backwards.
Car worked great for about six months though it did have a pretty obnoxious transmission whine that increased under speed. It was under warranty and I took it in to a dealer but two techs and the service manager claimed to have driven it around and could not reproduce the noise.... Could they all have been deaf? apparently.
One day my kid was driving home and the engine over temp light came on. Tried adding coolant to get it home but it was clear the head gasket had blown. The root cause was the thermostat housing had broken internally causing the seal to fail and coolant to leak out. On removing it, I also found the spring and clip that holds the metal disc in place was broken.
Looking around, I could see that I needed to pull the timing cover which in turn meant I had to pull the oil pan before I could remove the head. Since it was turning into a prolonged agony repair, I decided to go the whole hog and fix the transmission bearings also. It's my kid's car and somehow my labor appears to be free so why not. I removed the bumper and radiator pack to make the job easier. It was actually quite fun.
Upon removing my head, it looked like I had a small crack where one of the cylinder head bolts comes through. Given how much labor was involved, I didn't want to risk using it again so bought a refurbished head from here.
HEADSONLY | eBay Stores
It was great quality and worked fantastic but...... they had resurfaced it which according to GM is a big no-no. Why? Well, I used it but later discovered that it resulted in the top surface of the head sitting a little lower then the front timing cover so there was a small step there that resulted in a oil leak when the valve cover was installed. No big, and easily corrected with a small smooge of black silicone. Had I thought it through a little more before installing the head though, I would have bought a shim to correct the installed height from here
Innovative Machine & Supply - Cylinder Head Shims
The other thing to share is on tightening the cylinder head bolts. Some advice says to oil the threads and head of the bolts, while other advice says not to. I played the middle ground and just used a leedle WD40.... Heads-up, you do absolutely need to lubricate under the bolt head and the threads. I will use a graphite grease myself next time out. Why? Because on the last two 90deg turns in the tightening sequence, I was dealing with harsh noises that sounded like the creakiest garden gate of all time from a horror movie. Was freaking scary but I did get them tightened and it all worked out.
As for the transmission, I was lucky in that this car already had the newer style end case that provided more lubrication to the bearings. On dismantling it, I found that every single bearing in the transmission was pitted. The worst was the large lower mainshaft bearing that goes into the front housing by the differential. It was in very bad shape. This bearing would have been running in oil even if the low oil fill was an issue so..... did it fail because the regular GM transmission fluid overheats and fails? Or did all of them fail because any one bearing was shedding metal particles in the oil? I have no idea. When I completed my build, I used Redline MT90 oil which works great except the shifts are a bit notchy on real cold days until the trans warms up a little. My case temperature after a long drive is about 140F now.
For bearings, I got them and a bunch of different size shims from here
https://www.courtenaysport.co.uk/Popular-Items/M32-One-Stop-Gearbox-Shop/M32-Bearing-Kit-Late
This specific link is for the later type end housing so you need a different kit if you have the earlier style. Don't know what that means? Peruse the site and you'll figure it out. They have lots of good information there.
But..... that bearing kit comes with two identical Chinese NGBC front case bearings for the top and bottom mainshafts. One of these is wrong because the lower mainshaft has a trust bearing that runs on the back surface of the supplied taper bearing. The back surface of the NGBC bearing isn't big enough. To fix it, you need the correct *** bearing and the following link is for the latest version (#3) of this bearing. You only need 1ea, but I got 2ea because I had some concerns about the quality of the NGBC bearings.
https://www.ebay.com/itm/2-x-Fiat-55181940-M32-***-INA-Gearbox-Bearing-Replaces-Timken-NP238750-NP929800/173336252791?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
After installing all the bearings, it was time to shim the end case. For this operation, I didn't fully seat the three cups for the end case bearings. I pressed them in about 1/4" shy of the full seated position. I then installed the end case on to the front case with just five bolts and tightened them slowly while knocking on the cover by each bearing with a plastic mallet. When the bolts were fully tightened, I knocked on them all again and then verified that I could easily turn the input shaft through all gears by hand which I could. I also verified there was no apparent shaft play.
Then I measured under the bearing cups with feeler gauges to determine what size shims I needed. I them pulled the cups, installed the shims then put the cups back in. Next I reinstalled the cover with just a few bolts and verified that I could still easily turn the input shaft though all gears and there was no apparent play.
Lastly, I pulled the cover, cleaned the gasket surfaces and used a Permatex Anerobic sealant before reinstalling it. This sealant doesn't affect the bearing shimming by spacing out the cover, and excess sealant that is exposed to air will not harden. That's good on the inside because any smooge that breaks away will get absorbed by the oil and not block oil ways.
On initial startup, I was majorly concerned about how hot the engine was getting without the cooling fan running so spent quite a bit of time troubleshooting that same fan only to eventually find nothing was wrong. Turns out these engines run a lot hotter than the good old days and the fan doesn't turn on high speed until 230F. In normal operation, I might occasionally hit 230F briefly during driving after a cold start but it settles down to around 226F on light driving. The ECM does vary the temperature though so other times I'll average around 205F though I haven't figured out the logic.
It's all built back up and driving absolutely beautifully. Engine sounds sweet and FYI, I did also do the check valve modification to the intake manifold because I found the small rubber disc floating around inside when cleaning the throttle body. My last battle is a small oil leak that is dripping on to the exhaust manifold and having trouble finding the source. I replaced the O rings on the dipstick just this morning so hopefully that takes care of it.
Love, love, love this little car and my kid does also. I can tell it's going to be a bit demanding on the maintenance side but that's all good and having gone thought it as much as I have, I am confident that it is totally safe and reliable for her to drive.
The overall experience did nothing to negate my long standing negative impression of your average auto technician as I fixed a lot of their handiwork along the way. I know however that there are good and bad so wish everyone luck that they find a good one. I myself will keep fixing my own stuff even though I'm getting a bit too old for it.
Take care!
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