Joined
·
39 Posts
Sorry for the delay, just got to my office with the scanner. My cell is a POS...
Cylinder Head Problems - 3.7L specific only!
81 - 100 of 106 Posts
Joined
·
126 Posts
Thanks, the dealership said that the problem described in the letter is the only open item covered under warranty for my truck.
Makes me wonder if that particular issue could cause an intermittent P0300 and the problem I am experiencing. Either way, i'll just get the compression check done.
Joined
·
1,143 Posts
The root cause of GM Atlas engine valve failure is bad valve guides. The guides are dimensionally identical for all years but the guides in early heads (including early 3.7) failed prematurely. The guides are pressed in and are easily replaced with an upgraded version as part of a normal valve job. Any qualified machine shop that does heads can easily make them better than new!
Joined
·
39 Posts
Just got word that my truck is ready but the machine shop order shows "no parts, labor only"... If it is the valve guide, will a simple valve job solve the problem? Or did I just pay for a patch job?
Joined
·
1,143 Posts
A valve job will always include new valve seals but they are included in the gasket set and so they may not appear as parts related to a valve job. Valve guides can be repaired with a process similar to knurling but why when the wholesale cost of a new guide is like $2. each. Also why would anyone repair a guide that was no good when it was new?
My guess is that the dealer uses a "resale card" at the machine shop and the shop invoice to the dealer didn't include any tax just a lump price. With dealer mark-up I would expect their invoice to you included about $500. or so for the machine shop labor.
My guess is that the dealer uses a "resale card" at the machine shop and the shop invoice to the dealer didn't include any tax just a lump price. With dealer mark-up I would expect their invoice to you included about $500. or so for the machine shop labor.
Joined
·
39 Posts
Here is the invoice I received today from the shop. Keep in mind, they replaced the fan clutch, spark plugs, and did a minor service which is included in the overall price. Not as much as I thought it would be...
Joined
·
126 Posts
So for the valve issue alone, did they replace the valve guide that GCRuss was talking about? If they did and replacing the guides fixes the issue, then people with this problem can save a ton of money. Looks like most of the cost was labor, ~1300 dollars.
Wouldn't it make sense then to replace all the valve guides while the mechanics are in there?
Either way, if it's 100% confirmed that the materials shown in this pdf (related to the misfire) are all that is necessary to fix the "dreaded cylinder head problem," then i'll take this list to my mechanic and have them do it if it fails the compression check.
Also, Jon. This is really good info, many thanks!
Joined
·
39 Posts
No problem man! Glad to be able to shed some light on this. If this invoice helps you save some coin, I'm stoked. Hope it goes well for you. Let me know how it turns out!
Joined
·
126 Posts
I just ran the part numbers. I left the bolts out, but the other parts make no mention of new valve-related parts. The invoice just says "valve job."
GCRuss mentions that the valve seals are included in the gasket kit (89060396), but the valve guides are not mentioned on the invoice anywhere. Do we know if they were replaced? Do they need to be replaced to eliminate the issue?
89060396 GASKET - HEAD GASKET
12568766 SHOE - TIMING CHAIN GUIDE
12590962 GUIDE - CHAIN GUIDE
CYLINDER HEAD INSPECT & PRESSURE TEST CYLINDER - $281.25
HEAD. PERFORM VALVE JOB.
Sorry if I am asking a bunch of dumb questions. Like I said, if I (or others) have this issue, i'd like to create a list of parts that need to be replaced to fix it (for as little $$ as possible, obviously). I am seeing dealer quotes around this site for upwards of $3500 which seems like overkill, but it looks like it could be fixed for 40% less.
GCRuss mentions that the valve seals are included in the gasket kit (89060396), but the valve guides are not mentioned on the invoice anywhere. Do we know if they were replaced? Do they need to be replaced to eliminate the issue?
89060396 GASKET - HEAD GASKET
12568766 SHOE - TIMING CHAIN GUIDE
12590962 GUIDE - CHAIN GUIDE
CYLINDER HEAD INSPECT & PRESSURE TEST CYLINDER - $281.25
HEAD. PERFORM VALVE JOB.
Sorry if I am asking a bunch of dumb questions. Like I said, if I (or others) have this issue, i'd like to create a list of parts that need to be replaced to fix it (for as little $$ as possible, obviously). I am seeing dealer quotes around this site for upwards of $3500 which seems like overkill, but it looks like it could be fixed for 40% less.
Joined
·
39 Posts
From what I can gather, a standard valve job simply machines the seats and valves so that they seat properly. I can ask for the contact number for the machine shop they sent it to to ask exactly what they did. I like your plan.
Joined
·
1,143 Posts
It looks like they didn't mark-up the machine shop cost as the $281 would be a typical wholesale cost for a 5 cyl valve job. I am a little concerned that a new cam timing set (chain, guides, & hydraulic tensioner) and water pump were not installed while they were off. I would expect a typical dealer to charge at least $500. for the valve work so they were fair with you.
In the old OHV days valve guides were just holes in the cast iron head. When they were worn they were knurled and reamed back to size. Hot rodders frequently had aftermarket bushings installed in the valve guides for better high RPM valve control & reduced wear.
In the old OHV days valve guides were just holes in the cast iron head. When they were worn they were knurled and reamed back to size. Hot rodders frequently had aftermarket bushings installed in the valve guides for better high RPM valve control & reduced wear.
Joined
·
126 Posts
Compression results are in:
185 - Cyl 1
190 - Cyl 2
185 - Cyl 3
190 - Cyl 4
180 - Cyl 5
The thread discussing my truck in particular is here:
http://www.355nation.net/forum/engines-performance-tech-questions/181937-secondary-air-injection-idling-3-7l-08-a-3.html
185 - Cyl 1
190 - Cyl 2
185 - Cyl 3
190 - Cyl 4
180 - Cyl 5
The thread discussing my truck in particular is here:
http://www.355nation.net/forum/engines-performance-tech-questions/181937-secondary-air-injection-idling-3-7l-08-a-3.html
Joined
·
126 Posts
Probably a few years late, but the info in bold would be super helpful. Especially since the post quoted looks an awful lot like my issue.
Joined
·
1,143 Posts
The early motors have 10:1 compression & yours has 10.3:1. A good well sealed cylinder in either one should pump at least 200 lbs. You have one cylinder lower than the others but they are all showing signs on valve leakage which will only get worse.
The fix is a valve job and new (upgraded) valve guides. The ring, piston, & cylinder package on these engines seems to be excellent and provides a long useful service life so there is no need to go further than a valve job. That sucks considering the low truck mileage but it is worth repairing. Buying a used engine provides no confidence that it will be any better.
The fix is a valve job and new (upgraded) valve guides. The ring, piston, & cylinder package on these engines seems to be excellent and provides a long useful service life so there is no need to go further than a valve job. That sucks considering the low truck mileage but it is worth repairing. Buying a used engine provides no confidence that it will be any better.
Joined
·
126 Posts
Hey there Jon, its been a few weeks since your fix. Are all rough idle problems eliminated?
Joined
·
506 Posts
From this link the compression test should be 215 psig.
https://www.gmheritagecenter.com/do...ion-kits/Colorado/2004-Chevrolet-Colorado.pdf
This is for the 2.8L and 3.5L. I'd imagine the 3.7L should be higher since it is a higher CR.
Edit: They have the document for newer models as well. Compression test is 215 psig for the 2.9L and 3.7L.
https://www.gmheritagecenter.com/do...ion-kits/Colorado/2007-Chevrolet-Colorado.pdf
https://www.gmheritagecenter.com/do...ion-kits/Colorado/2004-Chevrolet-Colorado.pdf
This is for the 2.8L and 3.5L. I'd imagine the 3.7L should be higher since it is a higher CR.
Edit: They have the document for newer models as well. Compression test is 215 psig for the 2.9L and 3.7L.
https://www.gmheritagecenter.com/do...ion-kits/Colorado/2007-Chevrolet-Colorado.pdf
Joined
·
1,143 Posts
A problem is that most people are just getting leakdown tests which are not a true test of compression. A proper compression test can determine the actual pumping capability of a cylinder and it can differentiate whether the leak is the valves, the rings, or both.
A leakdown test just confirms that a leak exists. This tool originated in the 1960's as a quick check at the race track to see if you had damaged your engine between runs. Bent valves and broken springs were really common then. While it can provide confirmation that a major problem exists the result it is not a true diagnostic test. Why bother, just do a true compression test it only take a few minutes longer.
A leakdown test just confirms that a leak exists. This tool originated in the 1960's as a quick check at the race track to see if you had damaged your engine between runs. Bent valves and broken springs were really common then. While it can provide confirmation that a major problem exists the result it is not a true diagnostic test. Why bother, just do a true compression test it only take a few minutes longer.
Joined
·
24 Posts
Compression(psi). #1-188, #2-192, #3-188, #4-190, #5-188
Multiple misfire codes for all cylinders in the memory. Coils looked good, changed out plugs cause they were more fouled than they should be with 37k on the engine and it didn't help.
Having a shop do a valve job is not that much cheaper than getting a reman updated GM head with a year warranty. Is it going to actually be any better than what I have?
Any other good cylinder head companies? Rockauto has a new Famous Brand head for $760 but I don't know anything about them and can't find much. Spartan/ATK is $800.
Multiple misfire codes for all cylinders in the memory. Coils looked good, changed out plugs cause they were more fouled than they should be with 37k on the engine and it didn't help.
Having a shop do a valve job is not that much cheaper than getting a reman updated GM head with a year warranty. Is it going to actually be any better than what I have?
Any other good cylinder head companies? Rockauto has a new Famous Brand head for $760 but I don't know anything about them and can't find much. Spartan/ATK is $800.
Joined
·
1,143 Posts
Last time I looked the GM reconditioned head was just over $1,000. but you are in the Bay area of California and have lots of other options. Just a quick net search turned up three Cylinder Head shops in Oakland alone. I have no info on them but the Oakland shops are: American, Kings, & Bay Area. Personally I used Dynicron Cylinder Head in Stockton for mine last year. A valve job w/guides should be about $300-350. for an I5.
Joined
·
24 Posts
Russ- Gonna combine my answer to both of your responses, thanks for those btw.
The engine only has 37k miles on it so being down 23-27 psi from new and seeing misfires live with good coils and new plugs was what caused my mechanic to feel like it was a valve/guide issue. At that mileage I would hope that sensors and O2s aren't bad but you never know. It passed smog about a month ago and nothing else caught his eye when he did the deep scan of it.
As for the repair itself getting a new head is about $700 more than a valve job (in line with the numbers you quoted) so I agree that a valve job is probably the smarter move. I just wanted to check that I wouldn't be band-aiding a cylinder head with other problems that would show later. This is the only major work I want to do on this thing for another 120k (thought I already had a truck to do that).
There is actually a machine shop right by my mechanic but thank you for looking up those places.
The engine only has 37k miles on it so being down 23-27 psi from new and seeing misfires live with good coils and new plugs was what caused my mechanic to feel like it was a valve/guide issue. At that mileage I would hope that sensors and O2s aren't bad but you never know. It passed smog about a month ago and nothing else caught his eye when he did the deep scan of it.
As for the repair itself getting a new head is about $700 more than a valve job (in line with the numbers you quoted) so I agree that a valve job is probably the smarter move. I just wanted to check that I wouldn't be band-aiding a cylinder head with other problems that would show later. This is the only major work I want to do on this thing for another 120k (thought I already had a truck to do that).
There is actually a machine shop right by my mechanic but thank you for looking up those places.
81 - 100 of 106 Posts
