Rats - head gasket time
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,817
Likes: 1
From: Hartland WI
Rats - head gasket time
Ok, at this point I'm fairly certain its time for a new head gasket 
on my '88. Fortunatly, I have my handly Helms manual, and a reasonably competent son-in-law, so we are going to tackle this project ourselves. 
So - here go the questions.
1) Logic says we replace both sides as long we are tearing everything down - correct?
2) Since we will have the heads off anyway - is there anything special we should do with them - ie. is there any reason to send them out to a machine shop? What are the options for head work and what kind of costs?
3) What else should we be looking at since she'll be opened up?
car is an '88 vert, automatic - ALL STOCK. 60K I expect she will stay stock, with the possible exception of an exhaust system.
Thanks
on my '88. Fortunatly, I have my handly Helms manual, and a reasonably competent son-in-law, so we are going to tackle this project ourselves. So - here go the questions.
1) Logic says we replace both sides as long we are tearing everything down - correct?
2) Since we will have the heads off anyway - is there anything special we should do with them - ie. is there any reason to send them out to a machine shop? What are the options for head work and what kind of costs?
3) What else should we be looking at since she'll be opened up?
car is an '88 vert, automatic - ALL STOCK. 60K I expect she will stay stock, with the possible exception of an exhaust system.
Thanks
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,817
Likes: 1
From: Hartland WI
Originally Posted by IBEAM700
IMHO, if I had the heads off id install the LT4 valve springs and do the Comp Cams roller rockers 
Thoughts on cost? What are the benefits of that mod?
Thanks
Safety Car
Joined: Feb 2001
Posts: 4,397
Likes: 0
From: Looks like I picked the wrong week to stop sniffin glue Orlando
I haven’t priced the parts in a long time. I think the rockers are about 300, springs around 100, pushrods about another 100.
Benefits: You pick a couple of HP. 15 seems to be the going number ive found here on the board.
I’m sure the people that have actually done this can give you better numbers
Benefits: You pick a couple of HP. 15 seems to be the going number ive found here on the board.
I’m sure the people that have actually done this can give you better numbers
Drifting
Joined: Apr 2003
Posts: 1,292
Likes: 2
I am doing this too. (89 auto - thankfully not mine!)
1) Definitely. You are so nearly there with the manifold off and everything, not worth the risk of not checking both sides.
First, it may be the head gasket, in my case there is also a crack in one of the heads - which leads to -
2) while the heads are off, may as well put in new valve seals and grind the valves in, and while the valves are out send the heads for crack detection/skimming/valve guide inserts as necessary - after that performance stuff as suggested above
3) check bores for scoring, excessive wear (fingernail test at top of bore), broken top rings (flashlight and better eyes than mine), piston cracks etc.
1) Definitely. You are so nearly there with the manifold off and everything, not worth the risk of not checking both sides.
First, it may be the head gasket, in my case there is also a crack in one of the heads - which leads to -
2) while the heads are off, may as well put in new valve seals and grind the valves in, and while the valves are out send the heads for crack detection/skimming/valve guide inserts as necessary - after that performance stuff as suggested above
3) check bores for scoring, excessive wear (fingernail test at top of bore), broken top rings (flashlight and better eyes than mine), piston cracks etc.
Last edited by britvette; Feb 14, 2005 at 11:43 AM. Reason: typos
Safety Car
Joined: Feb 2001
Posts: 4,397
Likes: 0
From: Looks like I picked the wrong week to stop sniffin glue Orlando
Britvette brings up a good point. You might as well have them magnafluxed and checked for cracks while there off. Cheap insurance.
They’ll probable even hot-tank em for you.
They’ll probable even hot-tank em for you.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Since the heads are comming off:
-5-angle valve job
-2.00/1.56 valves
-hand pocket port
-1.6:1 ProMagnum RRs with Comp Cams 981 springs
Since you are doing the work, you only need to shape the valve guide boses, blend the seats into the bowls and remove any casting flashes for some gains.
The head work will gain 20-30hp, depending on how much porting is done; the RRs are worth 15chp.
You will get some of the benefit from those mods after you do the exhaust work.
BTW, while the hood is open, toss the "frisbee" from the front of the water pump pulley for a 10hp gain.
-5-angle valve job
-2.00/1.56 valves
-hand pocket port
-1.6:1 ProMagnum RRs with Comp Cams 981 springs
Since you are doing the work, you only need to shape the valve guide boses, blend the seats into the bowls and remove any casting flashes for some gains.
The head work will gain 20-30hp, depending on how much porting is done; the RRs are worth 15chp.
You will get some of the benefit from those mods after you do the exhaust work.
BTW, while the hood is open, toss the "frisbee" from the front of the water pump pulley for a 10hp gain.
Last edited by 65Z01; Feb 14, 2005 at 12:08 PM.
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Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,817
Likes: 1
From: Hartland WI
No - she's never overheated. I've been dealing with a "low coolant" light for a few months now, thought at first it was air in the system (burped it), or a defective sensor, but Saturday I noticed the green "Drip drip" up the the car after driving. An inspection found a small amount of coolant on the top of the engine near the #8 cylinder. I still want to pump it up with a pressure tester before tearing it all down, but I'm assuming thats the problem. I've alos started to notice more "white smoke" during warm-up, which since its winter I discounted at first, but now it looks like - well, you know.
Thanks for your help.
Thanks for your help.
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,817
Likes: 1
From: Hartland WI
Originally Posted by 65Z01
Since the heads are comming off:
-5-angle valve job
-2.00/1.56 valves
-hand pocket port
-1.6:1 ProMagnum RRs with Comp Cams 981 springs
The head work will gain 20-30hp, depending on how much porting is done; the RRs are worth 15chp.
You will get some of the benefit from those mods after you do the exhaust work.
BTW, while the hood is open, toss the "frisbee" from the front of the water pump pulley for a 10hp gain.
-5-angle valve job
-2.00/1.56 valves
-hand pocket port
-1.6:1 ProMagnum RRs with Comp Cams 981 springs
The head work will gain 20-30hp, depending on how much porting is done; the RRs are worth 15chp.
You will get some of the benefit from those mods after you do the exhaust work.
BTW, while the hood is open, toss the "frisbee" from the front of the water pump pulley for a 10hp gain.
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,817
Likes: 1
From: Hartland WI
Originally Posted by 65Z01
Is it possible that the coolant is comming up around the rear intake base bolt as there is a steam vent near that bolt.
Interesting - then I guess the question is a) is there a way to determine whether its the gasket or simply the bolt without disassembing everything? b) If everything has to be disassembled anyway would there be any reason not to just replace the gasket at that point?
Thanks
Racer
Joined: Jun 2001
Posts: 377
Likes: 10
From: Chicago IL
My 85 had the same symptoms and it was the intake gasket. leaking from all over the place - in and out. I'm a wannabe mechanic at best, but wouldn't a compression test help with the diagnosis of the head gasket?
Le Mans Master
Joined: Jun 2002
Posts: 6,097
Likes: 0
From: High Plains Drifter Fayetteville, AR
If it isn't broken, don't fix it. That's my motto.
As for determining where the leak is. Pressurize the cooling system with a pressure tester( usually one can be rented from the local parts house. For example autozone will rent one for $25, you bring it back and your $25 is returned to you) and remove the sparkplug for the cylinders in the area of the leak. Once pressure has bled down a little, crank the engine over and see if coolant comes out the plug holes.
If it's the intake manifold, try tighenting the bolts before doing anything else, that may be enough to seal the leak.
As for determining where the leak is. Pressurize the cooling system with a pressure tester( usually one can be rented from the local parts house. For example autozone will rent one for $25, you bring it back and your $25 is returned to you) and remove the sparkplug for the cylinders in the area of the leak. Once pressure has bled down a little, crank the engine over and see if coolant comes out the plug holes.
If it's the intake manifold, try tighenting the bolts before doing anything else, that may be enough to seal the leak.
Pro
Joined: Oct 2002
Posts: 586
Likes: 0
From: Schmuckville SA
I agree with JCAIRE2 and viii.. when I did my injectors, I decided to
check the torque on the intake (as I had done the intake gasket about
2 years previous).. Half of the bolts were loose where i could spin them
by hand.. Sounds like intake to me too...
check the torque on the intake (as I had done the intake gasket about
2 years previous).. Half of the bolts were loose where i could spin them
by hand.. Sounds like intake to me too...
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,817
Likes: 1
From: Hartland WI
Thanks guys - guess it would be time well spent to check the bolts first and do a little more diagnosis before tearing everything up.
The trouble with being "mechanically challenged" is that your bag of tricks (and diagnosis skills) are limited.
Thank heavens for CF!
The trouble with being "mechanically challenged" is that your bag of tricks (and diagnosis skills) are limited.
Thank heavens for CF!
Melting Slicks
Joined: Nov 2004
Posts: 2,799
Likes: 2
From: Cape Coral FL
Originally Posted by viii
My 85 had the same symptoms and it was the intake gasket. leaking from all over the place - in and out. I'm a wannabe mechanic at best, but wouldn't a compression test help with the diagnosis of the head gasket?
Burning Brakes
Joined: Nov 2000
Posts: 1,012
Likes: 1
From: Bowie MD
my L98 had both the intake leak, that I first fixed, then 6 months later paid to have the intake removed again to find I had the dreaded headgasket leak at the back of the cylinders. A combustion check as well as checking the antifreeze leaking out of the sparkplug hole once the engine was warm. My antifreeze leak never turned the oil funny colors, it just burnt off. Defintiely get heads checked by machine shop and go with there reccomendation for cleaning and redoing the rubber seals on the valves. The roller rockers and custom valve j0bs, and stronger springs only matter if your going for every bit of speed available. Otherwise it is a lot of money for little results. You could spend literally thousands on new heads, special porting jobs and new larger springs and valves. Do you just want the car to run well again at the lowest possible cost or do you want to sink a bunch of money, into a never ending project??? 
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
To check intake bolt tightness, set your torque wrench to 35lbs.
I picked up a cooling system pressure testor for around $100 and a compression gauge from Sears for <$50.
The investment in tools will come back in saved flat rates.
If you don't have the GM Shop Manual from HELM, now is the time to pick up a copy.
You will be surprised how quickly you become knowledgable.
I picked up a cooling system pressure testor for around $100 and a compression gauge from Sears for <$50.
The investment in tools will come back in saved flat rates.
If you don't have the GM Shop Manual from HELM, now is the time to pick up a copy.
You will be surprised how quickly you become knowledgable.