Chevrolet Colorado & GMC Canyon Forum banner
1 - 20 of 21 Posts

·
Registered
Joined
·
1,037 Posts
Discussion Starter · #1 ·
This 2004, 3.5L, 5-speed, 3.42-1 gear, extended cab, 2WD, Canyon was purchased new to be more of an economical work mule than a race horse. It was a little disappointing from the first day. Massive amounts of heat thru the passenger side floor required insulating the floor with a blanket for the first month. This did finally disappear as the dealer promised. Soon after but still under 3,000 miles intermittent starting problems required two trips to dealer to determine we had a defective battery.
Several years later the HVAC blower wiring & resistor burned up & I replaced all of it twice. Then the 2 1/2 year old battery died while shore launching (mud, no ramp) my boat at Edison Lake, high in the Sierra mountain back country. Luckily after removing the battery enclosure one of my boat batteries was coaxed into the battery space. After returning home I determined that a much larger battery would fit into available space and use the stock hold down and cables. The battery enclosure went into the trash. This was the end of ALL electric problems and that Costco Group 65 battery lasted almost 8 years.
Then the dreaded valve seat failure became public knowledge just as my truck approached the standard warrantee cut-off. Next I received the extended warrantee letter but soon that expired on mileage too. I worried about my head from then on. What could be so bad that a replacement of the head was required? Couldn't a good auto machine shop just install new seats? Were the heads repairable at all?
My questions were all answered after a failed compression test at 159,000 miles. Removing the head & taking it to a great machine shop I learned that the failure is ALWAYS just the easily replaced intake valve guides. Add a normal valve job & new oil seals & you are good to go. Mine head repair cost $325.00 total.
The MYTH that the valve seats fail is just wrong. If the valve seats were actually defective then repairing the heads probably wouldn't be cost effective. The very small diameter of the valve stems combined with sub-standard OEM guide material probably doom every I-4 & I-5 Atlas engine to early intake valve failure. In my opinion it's not if they will fail but how soon.
As of today with the new valve job my Canyon is actually running a little better than new. Next Monday the throttle body & PCM are shipping to SuperModulation for his famous updates also. I will be report in May about how it all worked out after towing my boat over 10,000 FT mountain passes several times for spring trout fishing.
 

·
Registered
Joined
·
1,037 Posts
Discussion Starter · #3 ·
Because I feel most people (including myself) have been told that the valve seats are the problem & that the head must be replaced. That is a major difference from just a normal valve job w/ replacement press-in guides. Also the very common electrical problems of the early model years could have been mostly prevented or remedied simply by cleaning all the grounding points and installing a bigger battery.
The next thing I post about this truck will be to report my comments on any improvements I obtain from my upcoming SuperModulation throttle body & PCM reflash w/reprogram. That post will be in Supermodulation's forum after towing my boat over steep mountain passes up to 10,000ft. That will be valuable insight that most people can't test but may find useful.
Knowledge is power, that said, I'm done.
 

·
Premium Member
Joined
·
5,710 Posts
I skimmed through this post and it seems pretty much duplicate to the other thread so I was curious.

You seem pretty adamant too that for all the years of failed heads that EVERYBODY has been lied to.

Is it at all possible that your high mileage motor developed it's own problem and is in fact not at all the same failure that plagued the motors 10 years ago?

I'm simply trying to understand. Usually when the valve seats are beat out it's evident and not easily confused for a valve stem seal failure. I have not personally experienced this nor have I seen one first hand, but for several years I've read the valve seat thing. Yes, a lot of time people just say those words but I have also heard that the inserts were crap which is why they have failed.
Kind of like when you run a 60's motor that isn't designed to run on unleaded fuel and beat out the valve seats.

Really, not trying to argue at all. The strong opinion of a single occurrence just makes me wonder.
 

·
maniac mechanic
Joined
·
5,767 Posts
That may have been your experience, but claiming it for everyone else would be foolish. I personally got to look at my bad head after it was replaced and it was certainly the seats not the valve guides as you claim.
 

·
Registered
Joined
·
1,037 Posts
Discussion Starter · #6 ·
Yes the seats do get beat-up after the guides fail but they are easily reground just like on any valve job. It wasn't that long ago that engines seldom lasted even 100,000 miles and needed a valve job in half of that. We just expect more now. Should we blame GM when our vehicles tend to come up short in a comparison with more expensive European or Asian vehicles? I think we got exactly what we paid for, in this case a flawed but adequate inexpensive vehicle that was designed by an international committee. I will keep mine and use up every single mile it has to give because it is adequate to complete the work I have for it. It just has taken a long time to get it fully sorted out. But in the end it is just another tool.
 

·
Premium Member
Joined
·
3,051 Posts
I read through your OP, several times, and still don't see where the "Valve Seat Myth" comment is justified. Your "history" doesn't indicate anything that a lot of people, driving many different brands, haven't experienced. Most all vehicles have a few peculiar weak spots. The HVAC blower control on the 355s is one of those. Batteries fail, that is not necessarily an issue with the truck. We have no way of knowing the quality of the parts used (batteries) or how the vehicle was driven and maintained.

As mentioned already, the "dreaded valve seat failure" issue was most prevalent on engines with less that 100,000 miles and worn valve guides at 160,000 would not be considered abnormal.

It doesn't appear the you busted the "Myth".
 

·
Registered
Joined
·
1,235 Posts
I read both posts you originated on this subject and it's not really debunking a myth. You're telling us something we already know...nothing real mind-blowing about 355 head issues. Some elect to replace the head & some get them rebuilt by machine shops. Depends on owner mechanical abilities & warranty coverage, but overall owner's choice on how they get their motor/head fix'd.

Thanks for the info, tho...always good to digest another 355 owner's experience(s).
 

·
Registered
Joined
·
1,037 Posts
Discussion Starter · #11 ·
For a do it your self on a 3.5L:
Head cost depending on source $300. - $1,200. (valve job v/s exchange GM head w/o deal)
Rock Auto prices: Valve job gasket set- Fel-Pro $130.79, head bolt set improved- Fel-Pro $52.79, & water pump- Delco $34.78 (too cheap to not replace when off)
From a GM dealer: Cam sprocket bolts- about $12.00
Buy local- RTV sealant, oil, oil filter, & coolant $50.-60.
Add shipping & tax ?
+ Fan clutch wrench, cam holding tool, damper puller, damper installer, & any other tool you don't have access to and also assuming you don't remove the radiator & a/c condenser. Personally I would never do this much work without also installing a timing set w/tensioner for another $95.79 (Rock Auto).

With a used engine you will not know its history or how soon it too will have valve problems. Also add the cost to evacuate, vacuum, & recharge the A/C system plus maybe a cherry picker rental. A used engine could be a faster installation though.
 

·
Premium Member
Joined
·
1,795 Posts
For a do it your self on a 3.5L:
Head cost depending on source $300. - $1,200. (valve job v/s exchange GM head w/o deal)
Rock Auto prices: Valve job gasket set- Fel-Pro $130.79, head bolt set improved- Fel-Pro $52.79, & water pump- Delco $34.78 (too cheap to not replace when off)
From a GM dealer: Cam sprocket bolts- about $12.00
Buy local- RTV sealant, oil, oil filter, & coolant $50.-60.
Add shipping & tax ?
+ Fan clutch wrench, cam holding tool, damper puller, damper installer, & any other tool you don't have access to and also assuming you don't remove the radiator & a/c condenser. Personally I would never do this much work without also installing a timing set w/tensioner for another $95.79 (Rock Auto).

With a used engine you will not know its history or how soon it too will have valve problems. Also add the cost to evacuate, vacuum, & recharge the A/C system plus maybe a cherry picker rental. A used engine could be a faster installation though.
Adding up your numbers for an actual repair, a $300 head job is not a good head job, especially on a uncommon motor. Expect these numbers:

Head: 1000
Gaskets: 130
Head bolts: 50
Water pump: 50 (ACDelco)
Cam Sprocket bolts: 12
Fluids: 100 (60 is really low balling it, oil alone is 30, filter is 5 for Delco, DEXTRON (MUST USE) 30, water is free, and this doesn't include RTV, etc)
Shipping: 100 (reasonable)
Tools to tear apart a DOHC inline: 100
Manual: 50-100

Total: $1600 in total repairs. THIS takes in to account you can retime a DOHC inline without the help of a shop and are comfortable taking apart the motor to this point. This doesn't include the extra time involved to do all the work yourself.

Most shop quotes: 3500-4000 <= totally reasonable quote to do head work on this complicated of a motor.

Growing up I worked on 4 cylinder detroits (scraper), 350 chevysv (rebuilds), 6 speed allison trannys (rebuilds, pump work, etc TS-14 Terex Scraper), 351 fords, 305 chevys, 4l60e valve bodies, 4.3L Vortec motor (rebuilds).

That's my history on motors. Back in September my original 3.5L had 206k miles on her when it seized. We could have torn it down, replaced the head that was causing issues, crank, bearings, etc but we didn't. Why? It doesn't make sense on these motors.

Here's why:
  • Junkyard motor from years WITHOUT known head issues are roughly 1000-3000
  • Respectable junkyards give warranties
  • You can't guarantee your own work (Murphy's Law)
  • If you fall in to the years with head issues, you can swap in a 2007 motor and have no issues and more power!

Last but not least, the time involved in the repair. Just how quick is a motor swap with 2 people in a 355?

We did it in 9 hours, no manual, no prior research other than fuel rail information. Started on Friday night, finished on Saturday afternoon.

Best part is...if you knew the motor ran before the junkyard pulled it, there isn't a trial period on whether or not you fucked up big time reinstalling that head.

That's why I went the route I did, and now I've got a truck with 220,000+ miles and only 107k on the motor. I have already put on 14k miles on since September with this new motor, including a 5400 mile trip to Florida.

you don't know the history of the old motor
ACTUALLY, you do. It's called carfax, and all vin numbers have one. A quick carfax can tell you if that truck was serviced at the dealer or not, but with most newer motors these days you can almost always assume 200k miles easily obtainable with the precise computer control and fuel injection implemented on all modern engines.
 

·
252,000+ Miles
Joined
·
1,313 Posts
If you look, the H3's actually had a TSB on the soft valve seats before the Twins did. Before they remedied it by replacing the entire head (and removing the existing heads from dealer inventory) they tried solving it for the Twins with valve spring replacements and something I can't remember.

The H3 TSB actually went into detail with how to remove and did replace the bad valve seats on the old heads, listed part numbers, and said specifically in the language that the spec the engineers has set for valve hardness was too low for actual in-service conditions.

My head was replaced for free at 79000 miles in late 2006. I had 35-55% compression in 3 cylinders, mid-80's on a 4th and a whopping 93% on the 5th.

Why don't the i6's have any issues with carbon build up, valve seat failure, valve guide, etc issues when the guts are the same?
 

·
Premium Member
Joined
·
3,345 Posts
I have to jump in here, because my 2005 has NEVER had the dreaded head issue. Everything on or in my 3.5 is stock except for the power steering pump, water pump and thermostat. My truck has 221000 miles, and if something on the head gave up today, I would be pretty sure it was just wear and tear. I do not think that one truck with issues at 159000 miles debunks any so called myth.

Just wondering how many other guys and gals on here have never had the head issue, have had the issue, and of the ones that had it, have never had any other problems from the head?
 

·
Premium Member
Joined
·
1,795 Posts
Mine never had the valve seat issue, all the way up until 206k miles. It seized for a completely irrelevant reason.

Compression numbers before the seize:
180
180
150
180
180

Cylinder number three had issues and it was using oil like crazy.
 

·
Registered
Joined
·
1,037 Posts
Discussion Starter · #18 ·
Colbyjohnson1994,
I stand by my numbers & clearly stated it was for do it yourself labor. I actually did spend more because while everything was accessible I also installed (new no recon) starter, alternator, thermostat, hoses, serpentine belt w/idler & tensioner, coil seal gaskets, & a timing set (chain, tensioner, & guides). I also decided to replace the cam timing solenoid which appeared a little marginal. The 5w-30 synthetic oil with Fram TG filter and coolant cost $38. total at Wal-Mart. Buying the OTC 6667 puller plus the parts to make a damper installer and cam holding tool was about another $80. Finally add the $331.12 for head reconditioning at Dynicron Cylinder Head Service (Stockton, CA.) and with the gasket set, water pump, bolts I'm at about $900.00 total.
Actually in hind sight I wish that I had installed a new A/C compressor & clutch while it was apart. I have the refrigerant, recovery tank, vacuum pump, & gauge set. Just like the truck the a/c system has been worked very hard too.
Although not a hot rod my truck is used much harder than most small trucks. It has seen at least 60,000 miles towing trailers over very steep & long California mountain passes, many times with the temp in excess of 100F. I think this expenditure of $900. may be the best money I ever spent on a vehicle & I expect another 100,000 trouble free miles.
Now I'm headed out to load the bed up fully for a dump run with green waste for recycling.
 

·
Premium Member
Joined
·
1,795 Posts
Colbyjohnson1994,
I stand by my numbers & clearly stated it was for do it yourself labor. I actually did spend more because while everything was accessible I also installed (new no recon) starter, alternator, thermostat, hoses, serpentine belt w/idler & tensioner, coil seal gaskets, & a timing set (chain, tensioner, & guides). I also decided to replace the cam timing solenoid which appeared a little marginal. The 5w-30 synthetic oil with Fram TG filter and coolant cost $38. total at Wal-Mart. Buying the OTC 6667 puller plus the parts to make a damper installer and cam holding tool was about another $80. Finally add the $331.12 for head reconditioning at Dynicron Cylinder Head Service (Stockton, CA.) and with the gasket set, water pump, bolts I'm at about $900.00 total.
Actually in hind sight I wish that I had installed a new A/C compressor & clutch while it was apart. I have the refrigerant, recovery tank, vacuum pump, & gauge set. Just like the truck the a/c system has been worked very hard too.
Although not a hot rod my truck is used much harder than most small trucks. It has seen at least 60,000 miles towing trailers over very steep & long California mountain passes, many times with the temp in excess of 100F. I think this expenditure of $900. may be the best money I ever spent on a vehicle & I expect another 100,000 trouble free miles.
Now I'm headed out to load the bed up fully for a dump run with green waste for recycling.
My truck gets used the same way, but in both extremes. South Dakota has 90-100 degree summers and below zero winters. This truck hauls trailers all year long, and through the black hills.

Here's where I'm going to say that your machine shop numbers are NOT normal. A machine shop anywhere else would cost 2-3 times what you paid of $300. I wouldn't trust a $300 head job in the conditions I drive my truck in, unless I was the one running the machine, checking the tolerances, etc.

All the parts you replaced while it was apart are things I never worried about, BECAUSE I was able to transfer over any part I needed to my new motor, which I did. I transferred anything I had ever replaced on that first motor over including: MAP sensor, ACDelco starter, and cam solenoid.

I put a new power steering pump in when I had it out, but honestly I would never rebuild one of these motors. This is simply because a. they are easy to find and b. by not replacing the head with the updated design you put yourself right back in the same bus you were in before! Just because you did valve guides, doesn't mean the valve seats aren't soft. Any motor that made it above 90k on the original head in the problem years are typically free from concern from valve seat issues, which is why it is good to find a motor that already made it past that point and has good history.

Plus...why not get gains for the same price? You could have easily swapped in a 3.7 from an 07 in half the time, the same cost, and had 40 free horsepower. Why the hell not?
 
1 - 20 of 21 Posts
Top