Time for a new head gasket? - Alfa Romeo Bulletin Board & Forums
 10Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 38 (permalink) Old 09-17-2015, 08:17 AM Thread Starter
Registered User
Gold Subscriber
 
gdpedersen's Avatar
 
Join Date: Jul 2006
Location: Des Moines, Iowa
Posts: 65
Time for a new head gasket?

After 15 years of relatively trouble free ownership, I've been chasing a poor-running condition in my '85 Graduate all summer. Symptoms are:
- poor idle, engine vibration
- low power, especially below 3k rpm
- backfire on aggressive throttle
- starts fine, hot or cold

I worked though Greg Gordon's excellent L-Jet diagnostics: checked vacuum leaks (new silicone hoses), cleaned grounds, new plugs cap and rotor, checked L-jet switches and sensors, had injectors cleaned by OKInjectors. No joy.

I finally got around to a compression test:
Cyl 4: 140 psi
Cyl 3: 136 psi
Cyl 2: 145 psi
Cyl 1: 0 (This could be the problem!)

No trace of coolant in the oil or oil in the coolant, but there is positive pressure in the valve cover. Valve timing seems to be right on, but when I take the oil filler cap off I get a lot air blowing out. That ain't right, is it?

So do you think I'm looking at my first head gasket project here, or could this be something else? Rings? Cracked head? Leaky valve? Any other tests I should do while its still running or do I just take the head off and see what I find?

Thanks for any advice on how to proceed!

Gene

85 Alfa Graduate
gdpedersen is offline  
Sponsored Links
Advertisement
 
post #2 of 38 (permalink) Old 09-17-2015, 10:26 AM
Registered User
 
Join Date: Jul 2008
Posts: 203
Gene, my understanding is that a head gasket starts to fail when you notice you're losing a significant amount of oil thru it... if you look mid way down the engine block on the driver's side, you'd see oil leaking from it, which gradually deteriorates so the oil and the coolant begin to mix and you can see brown froth in the coolant expansion tank..at which point you have to replace it.

The other symptoms you're describing are likely due to other factors, I think of rings...but since you have to go in there to address the cause...you should be replacing the head gasket and the rings and do a valve job and a new H2O pump as well, so you'd be addressing not only the probable causes but also replacing things that either need it or will shortly anyways.

'89 Spider Quad, "Rosa", original owner..still in love all these years...
grazie is offline  
post #3 of 38 (permalink) Old 09-17-2015, 10:51 AM
Registered User
 
Join Date: Jun 2013
Posts: 820
Quote:
Originally Posted by gdpedersen View Post
After 15 years of relatively trouble free ownership, I've been chasing a poor-running condition in my '85 Graduate all summer. Symptoms are:
- poor idle, engine vibration
- low power, especially below 3k rpm
- backfire on aggressive throttle
- starts fine, hot or cold

I worked though Greg Gordon's excellent L-Jet diagnostics: checked vacuum leaks (new silicone hoses), cleaned grounds, new plugs cap and rotor, checked L-jet switches and sensors, had injectors cleaned by OKInjectors. No joy.

I finally got around to a compression test:
Cyl 4: 140 psi
Cyl 3: 136 psi
Cyl 2: 145 psi
Cyl 1: 0 (This could be the problem!)

No trace of coolant in the oil or oil in the coolant, but there is positive pressure in the valve cover. Valve timing seems to be right on, but when I take the oil filler cap off I get a lot air blowing out. That ain't right, is it?

So do you think I'm looking at my first head gasket project here, or could this be something else? Rings? Cracked head? Leaky valve? Any other tests I should do while its still running or do I just take the head off and see what I find?

Thanks for any advice on how to proceed!

Gene
first... a leakdown will tell you your answer in absolute terms but from a symptom stand point, a hg doesn't generally manifest itself as a zero compression result in one cylinder. they will either fail cyl to cyl which gives you two bad numbers or they fail to coolant or oil which gives you smoke and some other obvious symptom. a zero compression on a single cylinder with hi crank case pressure sounds more like a piston or ring failure... but, never the less , a leakdown will tell you your answer... and is this cyl really absolute zero ? like no needle movement at all ? that's pretty serious if that's the case...
stevesxm is offline  
Sponsored Links
Advertisement
 
post #4 of 38 (permalink) Old 09-17-2015, 10:54 AM
Senior Member
Platinum Subscriber
 
alfaparticle's Avatar
 
Join Date: Oct 2004
Location: Columbia SC
Posts: 12,942
The two times that I had readings like those, I had a burned exhaust valve. Pull the cam cover and check the valve clearances.
Norseman50 likes this.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
alfaparticle is offline  
post #5 of 38 (permalink) Old 09-17-2015, 10:55 AM
Registered User
Gold Subscriber
 
rogerspeed's Avatar
 
Join Date: May 2005
Location: OC CA USA
Posts: 3,585
take off the valve cover gasket and measure the valve clearances, your engine may be "eating" a valve. The head is going to come off either way, but it is a good idea to have as much knowledge as possible going in.

current:
84 Spider Veloce
ex:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

solve problems, learn something new!
rogerspeed is offline  
post #6 of 38 (permalink) Old 09-17-2015, 11:17 AM
Registered User
 
Join Date: Jun 2013
Posts: 820
Quote:
Originally Posted by alfaparticle View Post
The two times that I had readings like those, I had a burned exhaust valve. Pull the cam cover and check the valve clearances.
burned valve wouldn't give you crank case pressure though , wouldn't you think ?
stevesxm is offline  
post #7 of 38 (permalink) Old 09-17-2015, 11:35 AM
Senior Member
Platinum Subscriber
 
alfaparticle's Avatar
 
Join Date: Oct 2004
Location: Columbia SC
Posts: 12,942
Maybe some blow-by too. It is common with higher mileage engines.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
alfaparticle is offline  
post #8 of 38 (permalink) Old 09-17-2015, 11:46 AM Thread Starter
Registered User
Gold Subscriber
 
gdpedersen's Avatar
 
Join Date: Jul 2006
Location: Des Moines, Iowa
Posts: 65
Thanks to everyone for the ideas.

On No. 1 the compression gauge needle does not move at all. I guess I need to figure out how to do a leak-down test. I can sorta see the exhaust valve in it's open position through the spark plug hole and it doesn't look right -- like it's either eaten away or has crusty deposits on it. Hard to get a good look. I'll check the clearances when I get the cover off.

Seems odd that rings in one cylinder would fail so completely before the others, doesn't it? The car has about 120k miles on it. I don't think the head has ever been off. I'm confident I can replace the head gasket. Rings and/or liners... not so sure. And here in Iowa, Alfa mechanics are a little scarce.

85 Alfa Graduate

Last edited by gdpedersen; 09-17-2015 at 11:57 AM.
gdpedersen is offline  
post #9 of 38 (permalink) Old 09-17-2015, 12:18 PM
Registered User
 
Join Date: Jun 2013
Posts: 820
Quote:
Originally Posted by gdpedersen View Post
Thanks to everyone for the ideas.

On No. 1 the compression gauge needle does not move at all. I guess I need to figure out how to do a leak-down test. I can sorta see the exhaust valve in it's open position through the spark plug hole and it doesn't look right -- like it's either eaten away or has crusty deposits on it. Hard to get a good look. I'll check the clearances when I get the cover off.

Seems odd that rings in one cylinder would fail so completely before the others, doesn't it? The car has about 120k miles on it. I don't think the head has ever been off. I'm confident I can replace the head gasket. Rings and/or liners... not so sure. And here in Iowa, Alfa mechanics are a little scarce.
well ... at 120 k with a zero cylinder , I would say that any further testing is a waste of time really. just take it apart and do the freshening and be done with it.
Norseman50 likes this.
stevesxm is offline  
post #10 of 38 (permalink) Old 09-17-2015, 12:48 PM Thread Starter
Registered User
Gold Subscriber
 
gdpedersen's Avatar
 
Join Date: Jul 2006
Location: Des Moines, Iowa
Posts: 65
Steve,
That's what I wanted to hear, I'm anxious to get started. I'll either fix it or I'll have to shoot it.

85 Alfa Graduate
gdpedersen is offline  
post #11 of 38 (permalink) Old 09-17-2015, 01:14 PM
Registered User
 
Join Date: Jun 2013
Posts: 820
Quote:
Originally Posted by gdpedersen View Post
Steve,
That's what I wanted to hear, I'm anxious to get started. I'll either fix it or I'll have to shoot it.
if its a nice car as far as rust free etc, then its worth the few hundred in parts to do rings , bearings , gaskets and a proper valve job and have a neat car to drive. its not a hard job and there aren't any real tricks to it. simple mechanics 101. the trick will be not to get caught up in the whole alfa mythology. get a good and proper service manual and pay attention and you will be fine.

I posted a link a week or so ago under the title " this seems cheap to me " where a guy in ca was selling what was ostensibly a low mileage driveline for give away money. you could probably buy that and get it trucked to where you are for the same money this rebuild will cost you if you grind on him hard enough...

Last edited by stevesxm; 09-17-2015 at 01:17 PM.
stevesxm is offline  
post #12 of 38 (permalink) Old 09-17-2015, 02:56 PM
Registered User
Gold Subscriber
 
rogerspeed's Avatar
 
Join Date: May 2005
Location: OC CA USA
Posts: 3,585
if the valve clearance is not checked and maintained periodically the engine will eat a valve and in the process ruin cam and tappet, the remains of which end up in the oil causing mischief. So as Ed suggested measure the valve clearances before you take everything apart so you have a baseline and keep track of where everything came from. I like spare engines, but who knows what inside the engine for sale on craigslist?

current:
84 Spider Veloce
ex:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

solve problems, learn something new!
rogerspeed is offline  
post #13 of 38 (permalink) Old 09-17-2015, 03:39 PM
Registered User
 
Join Date: Jun 2013
Posts: 820
Quote:
Originally Posted by rogerspeed View Post
if the valve clearance is not checked and maintained periodically the engine will eat a valve and in the process ruin cam and tappet, the remains of which end up in the oil causing mischief. So as Ed suggested measure the valve clearances before you take everything apart so you have a baseline and keep track of where everything came from. I like spare engines, but who knows what inside the engine for sale on craigslist?
well... if he does a valve job when he's doing this, the original clearences will be meaningless info because they will all be wildly different when he's done and as long as he keeps track of where the followers come from ( mechanics 101 ) then if they were good before then they ( and the cam ) will be good again. as for the used motor... you do a bore inspection , a valve clearance check, a leak down and sniff the oil and you can know with about 90 % certainty what you are buying. its standard practice.
stevesxm is offline  
post #14 of 38 (permalink) Old 09-17-2015, 06:44 PM
Registered User
Gold Subscriber
 
rogerspeed's Avatar
 
Join Date: May 2005
Location: OC CA USA
Posts: 3,585
No worries, I try to follow, what some call "best practices" as exemplified by the old adage, measure twice, cut once; though when it comes to an aluminum head that is not straight, press first.

current:
84 Spider Veloce
ex:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

solve problems, learn something new!
rogerspeed is offline  
post #15 of 38 (permalink) Old 09-17-2015, 08:09 PM
Registered User
 
kcabpilot's Avatar
 
Join Date: May 2003
Location: Antioch CA
Posts: 4,288
Well if you've really got zero compression on #1 then put it at TDC on compression stroke and have someone blow compressed air in the spark plug hole. You'll hear it coming out either the throttle, the tailpipe or the crankcase when you open the oil filler. That will tell you what's going on.
Norseman50 likes this.

Paul - 1972 Spider - (2)1991 164S's - 1983 308 - 2001 Discovery - 1997 F350
kcabpilot is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Alfa Romeo Bulletin Board & Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may 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

 
For the best viewing experience please update your browser to Google Chrome