Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner
1 - 10 of 10 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
Well buys this is my first post,i dont know where to turn.My family and i were coming home from Myrtle Beach when wew heard a tapping sound coming from top of engine.I took it to my mechanic he told me it was a collpases valve adjuster ,to make a long story short he replaced 8 of them and told me after that none of the 8 would pump and and he didnt know what to do.so after 500 dollars in repairs our beloved trailblazer sounds like a diesel,much worse than it did.my questipon is can i replace these myself.i would appreciate any advice guys.Why wouldnt they pump up.
 

·
Registered
2005 chevy trailblazer_ls
Joined
·
1,733 Posts
:tiphatFirst let me say welcome to the site! Although I can't help with your problem, don't give up as we have several very knowledgeable people on here that will chime in as they log on and check the site and I'm sure you will get the info you need! Once again let me welcome you to the best forum on the web!!:tiphat
 

·
Registered
2009 chevy
Joined
·
6,431 Posts
It has become my practise, to skip over threads where the poster does not fill out the vehicle information.

But, I'm making an exception, in this case.

I'm posting, so that you, and others that may read this, will appreciate the value of this information.

Your asking a question about your engine, 2 engines types are available.

Which one do you have?????????

Now, I know it must be a V-8, the I-6 does not have lifters.

However, if you do have a V-8 and lifters were changed, there are 16 of them, and only 8 were changed.

So, fill out the profile, please, and come back and talk to us.
 

·
Premium Member
2007 chevy trailblazer_ls
Joined
·
1,422 Posts
Also hate to say this but were they adjusted properly when installed?
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #6 ·
Sorry guys just filled out cp,
It is 4.2 I6 ,8 valve lash adjusters were replaced after they were replaced the mechanic told me he had no idea what the problem was and would not have a whole lot of time to look at it !!!
He told me they would not pump up
 

·
Registered
2002 gmc envoy_slt
Joined
·
3,203 Posts
Why did he replace 8 of them? ...... You would have sounded like a diesel engine with 8 bad units to begin with. My guess would be they incorrectly installed or prepped by the mechanic and the diesel noise is the valve abruptly closing, which isn't good for the valve itself. (They need to close under a controlled motion or rate or valve damage could potentially occur). From the sounds of it, your mechanic may have made things worse!

I haven't had to work on a 4.2, however in general hydraulic valve lash adjusters (or tappets) do not work identical to the old style lifters. While they do resemble and operate on a similar principle to a lifter, they don't 'pump up' via compression, which is what your mechanic I believe was trying to do. (Might be time to find a mechanic who better understands OHC engines). You soak tem in diesel fuel and using a small allen wrench or stiff wire, push in the check-ball (check-valve). You should see bubbles come out, indicating oil has enterred the adjuster. (You don't 'pump' them up per se, like you would a lifter using an old push rod, while immersed in oil). Once fully purged of air and filled with diesel fue/thin oil, they're ready for installation. Our adjusters hold the roller cam follower in contact with the camshaft lobes, by pushing up on the pivet end of the follower.

This is something that I would attempt in my driveway, however whether you could perform this task depends upon your mechanic skills. Not the most difficult task, but it takes some understanding of the workings of an OHC engine. As I said, I haven't worked on the valvtrain of a 4.2, so I'm not positive whether the camshafts need to be pulled in order to replace the adjusters/tappets. On some engines they do and others they don't, however based upon the pictures and diagrams I've seen, my guess is that camshaft removal would be needed in order to replace them.....so you need to be able to mechanically time the cams and crankshaft when re-installing the timing chain.
 

·
Registered
2009 chevy
Joined
·
6,431 Posts
:iagree:with ylab, but I'm wondering if the problem is (maybe I should say was) with the lash adjusters. Perhaps, and this is just a maybe, you might have a problem with the variable valve timing. I have heard, if not working properly the engine can sound like a diesel :undecided
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #9 · (Edited)
Thank's alot guys i really appreciate youre input.i agree with you ylab i have already found another mechanic(local chevy dealer).it goes in tomorow.I guess i will wait for the huge bill(but hopefully it will be done right).
I do really appreciate you guys taking time out youre busy lives to help.
Thanks rayvoy i had someone else say sme thing
 
1 - 10 of 10 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top