Exhaust Valve toasted? - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 01-16-2010, 03:52 PM   #1
Newb
Thread Starter
 
Join Date: Aug 2008
Location: San Diego
Posts: 30
Total Cats: 0
Default Exhaust Valve toasted?

I have a problem with my car, but don't know how it happened. The issue would be burnt exhaust valve in #1 cylinder.
Here's how it went down. Got up early this morning 5AM to start heading up to Fontana for a track day. 30 miles from the house with 1/4 tank i decide to get some gas (91 octane fill-up) to make sure i can get all the way to the track without having to stop. Got back on the 5 freeway north and cruised @ 85mph for 5 or 6 minutes all of the sudden it start running rough out of the blue. I decided to turn around in Del Mar and limp the car home. Did a Compression test shows and #1 cylinder has 0 psi , the rest of the cylinders show 135/140/140. I pour some oil into #1 cylinder to see if its the rings, but still 0 psi. I bring the motor to TDC and hook up the leak-down tester and maxed out the pressure to see if i could determine where the problem is but at 55 psi i could not really determine where the problem is. so i reinstalled the compression tester minus the gage and hook it up the compressor air hose. the line pressure is set at 90 psi. Checked from the oil filler, not much noise. Checked at the TB wide open also not much noise. Go to the exhaust and you can feel the air coming out from there. So now i believe some how i burnt an exhaust valve. Gonna have to pull the head to confirm though.
Has this ever heard of this happening before, while cruising at a steady state?
Thank you all in advance, for all/any inputs.
Evolforce2 is offline   Reply With Quote
Old 01-16-2010, 09:01 PM   #2
Junior Member
iTrader: (1)
 
Join Date: Apr 2008
Location: Bristol
Posts: 442
Total Cats: 0
Default

Quote:
Originally Posted by Evolforce2 View Post
Has this ever heard of this happening before, while cruising at a steady state?
Thank you all in advance, for all/any inputs.
If you have det or very high egt then you will toast a valve regardless of whether you are cruising or under full load.

What engine management and engine mods are you running? Come to think of it fill out your sig with you cars full spec too!
Duckie_uk is offline   Reply With Quote
Old 01-16-2010, 09:21 PM   #3
Elite Member
iTrader: (8)
 
Join Date: Aug 2007
Location: Bellingham, Wa
Posts: 2,732
Total Cats: 3
Default

I burnt an exhaust valve in our 100% stock integra driving up a mountain. It was a steady cruise but a very steep hill so lots of load.


Name:  Picture046.jpg
Views: 63
Size:  62.5 KB

My machinist actually suggested that high carbon buildup can cause burnt valves too if some breaks loose and gets into the valve seat preventing it from sealing.
wayne_curr is offline   Reply With Quote
Old 01-17-2010, 03:02 AM   #4
Newb
Thread Starter
 
Join Date: Aug 2008
Location: San Diego
Posts: 30
Total Cats: 0
Default

Opps OK Sig inserted.
No detonation, on level freeway with light load.
Had the car running in this set-up for over 6 months while i gather last few items and money to finish my turbo project.

THX Wayne, so it is totally possiable :( hopefully i can have the head off soon.
Evolforce2 is offline   Reply With Quote
Old 01-17-2010, 04:34 AM   #5
Junior Member
iTrader: (1)
 
Join Date: Apr 2008
Location: Bristol
Posts: 442
Total Cats: 0
Default

Quote:
Originally Posted by wayne_curr View Post
My machinist actually suggested that high carbon buildup can cause burnt valves too if some breaks loose and gets into the valve seat preventing it from sealing.
Carbon can also produce hot spots in the chamber that will kick off det.

Evolforce, how can you be sure that there was no det? You could have filled up with some shonkey gas and been pinging slightly all the way and never known unless you were wearing some of hustler's stylish cans.
Duckie_uk is offline   Reply With Quote
Old 01-17-2010, 10:46 AM   #6
Newb
Thread Starter
 
Join Date: Aug 2008
Location: San Diego
Posts: 30
Total Cats: 0
Default

Duckie,
Thks. I could have been pinging all the while and not known it, but i remember the sound of det. as if you were to take a sheet of aluminum foil and ball it up quickly. The sound will not last long till you see a lot of smoke coming out the exhaust as a result of det breaking the ring lands :(. So where do i get some of those "hustler's stylish cans"? lol
I have an up date in a few day all. Again thanks for the input all.
Evolforce2 is offline   Reply With Quote
Old 01-17-2010, 11:26 AM   #7
Elite Member
 
Join Date: Jul 2005
Posts: 6,454
Total Cats: 80
Default

A loose valve guide can cause premature valve failure.
JasonC SBB is offline   Reply With Quote
Old 01-17-2010, 12:22 PM   #8
Junior Member
iTrader: (1)
 
Join Date: Apr 2008
Location: Bristol
Posts: 442
Total Cats: 0
Default

Hustler cans consist of a piece of tube hammered flat with a hole drilled in it connected to a length of hose that runs into the cockpit and then in to a pair of standard ear defenders. The tube is screwed to the block just above the engine mount on the passenger side. Lots of people swear by them for ironing out spark tables. And some people prefer the electric version using a microphone, amp and conventional headphones. Mostly because they don't look so ghetto.
Duckie_uk is offline   Reply With Quote
Old 01-17-2010, 01:12 PM   #9
Elite Member
iTrader: (9)
 
TurboTim's Avatar
 
Join Date: Jun 2006
Location: Chesterfield, NJ
Posts: 6,484
Total Cats: 248
Default

Quote:
Originally Posted by Evolforce2 View Post
I have a problem with my car, but don't know how it happened. The issue would be burnt exhaust valve in #1 cylinder.
Here's how it went down. Got up early this morning 5AM to start heading up to Fontana for a track day. 30 miles from the house with 1/4 tank i decide to get some gas (91 octane fill-up) to make sure i can get all the way to the track without having to stop. Got back on the 5 freeway north and cruised @ 85mph for 5 or 6 minutes all of the sudden it start running rough out of the blue. I decided to turn around in Del Mar and limp the car home. Did a Compression test shows and #1 cylinder has 0 psi , the rest of the cylinders show 135/140/140. I pour some oil into #1 cylinder to see if its the rings, but still 0 psi. I bring the motor to TDC and hook up the leak-down tester and maxed out the pressure to see if i could determine where the problem is but at 55 psi i could not really determine where the problem is. so i reinstalled the compression tester minus the gage and hook it up the compressor air hose. the line pressure is set at 90 psi. Checked from the oil filler, not much noise. Checked at the TB wide open also not much noise. Go to the exhaust and you can feel the air coming out from there. So now i believe some how i burnt an exhaust valve. Gonna have to pull the head to confirm though.
Has this ever heard of this happening before, while cruising at a steady state?
Thank you all in advance, for all/any inputs.
The exact same thing happened to me last thursday, but in my subaru. We did the same tests (no increase when oil added to cyl, air leaks out exhaust when cyl at TDC on compression stroke). We think it's the exhaust valve on that cyl too. So far it only misfires at idle (85psi in the bad cyl) so hopefully it will last thru the snow season. Or I just won't go to work if it snows.

Let us know what you find out.
TurboTim is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 57 07-19-2017 05:11 PM
Another Cast Manifold Corky Bell Prefabbed Turbo Kits 18 11-22-2016 10:01 PM
OTS Bilstein to motorsports ASN conversion stoves Suspension, Brakes, Drivetrain 5 04-21-2016 04:00 PM
1996 Turbo Build Goldwar DIY Turbo Discussion 2 09-29-2015 10:20 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 06:04 PM.