Replacing the Heads on a L98 (86 C4)
05-05-2011, 01:12 PM
#21
C4's arent quite to the investment level, but being interested, and able to do the work yourself will give you satisfaction, you came to the right site, there's an amazing amount of knowledge here and they're great about giving back, respect to all of you, bob
05-05-2011, 06:37 PM
#22
something I havent checked alot into , the last 100 or so 87's came with 113 heads , 86/87 are pretty close on parts matchup and you can get a set of those reaonably priced. It would lower your front end weight and with a good rebuild give some good numbers with out breaking the bank.
05-05-2011, 10:54 PM
#23
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The results are in and....
#1 - 107
#2 - 63
#3 - 54
#4 - 52
#5 - 70
#6 - 54
#7 - 65
#8 - 72
I'm assuming good compression is in the 180-190 PSI range... given 10:1
Didn't need to add oil because there was enough already. Thanks valve seals! Consider the results cold and wet.
I put the plugs back in and tried to start it up and I got one little putter. I kept trying and may have fried the starter motor. After about a minute or two on on and off trying ithe starter just just "clicked"
. I think I have enough juice with my new 200A starter/charger so the battery is not the issue. The starter is warm to the touch. I just let it be and I'll give it a go in the morning.
None the less I think the motor is %$&#ed!
Has any one heard of a head gasket blowing, losing compression but no coolant in the oil?
I really don't want to pull this beast given a used motor is in the 1.5 to 2K range. I don't want to take the time needed to rebuid the bottom end either.
At this points it might be heads or bust. Unless someone has a lead on a cheap motor...
Any help is greatly appreciated.
Lucky Kid
#1 - 107
#2 - 63
#3 - 54
#4 - 52
#5 - 70
#6 - 54
#7 - 65
#8 - 72
I'm assuming good compression is in the 180-190 PSI range... given 10:1
Didn't need to add oil because there was enough already. Thanks valve seals! Consider the results cold and wet.
I put the plugs back in and tried to start it up and I got one little putter. I kept trying and may have fried the starter motor. After about a minute or two on on and off trying ithe starter just just "clicked"
. I think I have enough juice with my new 200A starter/charger so the battery is not the issue. The starter is warm to the touch. I just let it be and I'll give it a go in the morning.None the less I think the motor is %$&#ed!
Has any one heard of a head gasket blowing, losing compression but no coolant in the oil?
I really don't want to pull this beast given a used motor is in the 1.5 to 2K range. I don't want to take the time needed to rebuid the bottom end either.
At this points it might be heads or bust. Unless someone has a lead on a cheap motor...
Any help is greatly appreciated.
Lucky Kid
05-06-2011, 12:19 AM
#24
that low of compression, squirt oil in each cylinder and see if the compression improves, if it doesnt improve its valves, if it improves its rings, then check the valve lash cold, if the previous owner thought he was mechanical , and wasnt, he could have adjusted the valves to tight. in my shop I spent alot of time , fixing things.
05-06-2011, 01:38 AM
#25
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St. Jude Donor '05
Get the car warm then try it again.
make sure you can spin the motor over quickly meaning healthy battery
make sure you can spin the motor over quickly meaning healthy battery
Last edited by cv67; 05-06-2011 at 01:46 AM.
05-06-2011, 06:41 AM
#26
Burning Brakes
OMG, this all brings back memories of pulling my motor apart...the first time. I go so frustrated with it I just sent the thing out. When I pulled off my driver side head, I had a nice pool of coolant in my #7 piston, and #1 looked like I shot off mortars for 4th of July out of it.
I would figure out exactly how much you want to spend. Most bang for your buck would be some heads. The old standby is Edelbrock, but I'm sure there is some knowledge here that can be cheaper. If the old lady is REALLY serious about getting rid of it, that's all I would do. Doing a full pick, teardown and rebuild to do your valvetrain will take longer than expected. Don't forget about our old friend Murphy and his dam laws.
Pull heads
Clean deck and pistons
Put new heads on
Mash gas
Take lots of pics and LABLE EVERY SINGLE STUIPD VACCUME LINE, RANDOM COOLANT TUBE AND WHATEVER CRAZY AND POSSIBLY RANDOM STUFF that they put on TPi. You'd be more than suprised.
*edit*
I didn't read the second page.
I would say too tight valves. I've seen Ford guys do this ALOT. Nothing against the guys, I consider myself both a Ford and Chevy guy. Just not MOPAR. The old F-100s get a lot of ticking.
As far as the blown head gasket, I've seen some strange stuff (again on a Ford). A buddy who had a 5.0 overheated..... severely. We pulled the heads. The port through which the coolant flows had a perfectly round piece of gasket. Looked like a bolt gasket. The rest of that section was G-O-N-E. I'm pretty sure this isn't common....at all. Probably a fluke. Just letting you know that some crazy stuff can happen. Remember Murphy?
I would figure out exactly how much you want to spend. Most bang for your buck would be some heads. The old standby is Edelbrock, but I'm sure there is some knowledge here that can be cheaper. If the old lady is REALLY serious about getting rid of it, that's all I would do. Doing a full pick, teardown and rebuild to do your valvetrain will take longer than expected. Don't forget about our old friend Murphy and his dam laws.
Pull heads
Clean deck and pistons
Put new heads on
Mash gas
Take lots of pics and LABLE EVERY SINGLE STUIPD VACCUME LINE, RANDOM COOLANT TUBE AND WHATEVER CRAZY AND POSSIBLY RANDOM STUFF that they put on TPi. You'd be more than suprised.
*edit*
I didn't read the second page.
that low of compression, squirt oil in each cylinder and see if the compression improves, if it doesnt improve its valves, if it improves its rings, then check the valve lash cold, if the previous owner thought he was mechanical , and wasnt, he could have adjusted the valves to tight. in my shop I spent alot of time , fixing things.
As far as the blown head gasket, I've seen some strange stuff (again on a Ford). A buddy who had a 5.0 overheated..... severely. We pulled the heads. The port through which the coolant flows had a perfectly round piece of gasket. Looked like a bolt gasket. The rest of that section was G-O-N-E. I'm pretty sure this isn't common....at all. Probably a fluke. Just letting you know that some crazy stuff can happen. Remember Murphy?
Last edited by navy_vette; 05-06-2011 at 06:52 AM.
05-06-2011, 07:43 AM
#27
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St. Jude Donor '05
What alaskaman is getting at is if the valves are adisted too tight the valves can hang open.
Fords blow head gaskets at least some of them a little easier as there are less head bolts surroinding the cyl so less clamping force.
I sincerely doubt an L98 is going to make around 200lbs cyl pressure.
Fords blow head gaskets at least some of them a little easier as there are less head bolts surroinding the cyl so less clamping force.
I sincerely doubt an L98 is going to make around 200lbs cyl pressure.
05-06-2011, 08:36 AM
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that low of compression, squirt oil in each cylinder and see if the compression improves, if it doesnt improve its valves, if it improves its rings, then check the valve lash cold, if the previous owner thought he was mechanical , and wasnt, he could have adjusted the valves to tight. in my shop I spent alot of time , fixing things.
I'd imagine I can check lash, just by pulling the valve covers. Any good write ups on this?
There are photos with the valve covers off and write ups, but I physically don't know where to measure and what tools to use. The basic stuff is obvious once you know it, but you don't what to know how long it took me to find online what piston is #1 and how they are numbered.
Get the car warm then try it again.
make sure you can spin the motor over quickly meaning healthy battery
make sure you can spin the motor over quickly meaning healthy battery
I would figure out exactly how much you want to spend. Most bang for your buck would be some heads. The old standby is Edelbrock, but I'm sure there is some knowledge here that can be cheaper. If the old lady is REALLY serious about getting rid of it, that's all I would do. Doing a full pick, teardown and rebuild to do your valvetrain will take longer than expected. Don't forget about our old friend Murphy and his dam laws.
Pull heads
Clean deck and pistons
Put new heads on
Mash gas
Take lots of pics and LABLE EVERY SINGLE STUIPD VACCUME LINE, RANDOM COOLANT TUBE AND WHATEVER CRAZY AND POSSIBLY RANDOM STUFF that they put on TPi. You'd be more than suprised.
Pull heads
Clean deck and pistons
Put new heads on
Mash gas
Take lots of pics and LABLE EVERY SINGLE STUIPD VACCUME LINE, RANDOM COOLANT TUBE AND WHATEVER CRAZY AND POSSIBLY RANDOM STUFF that they put on TPi. You'd be more than suprised.
I think she's going up on craigslist after work, while I try to figure out the issues.
05-06-2011, 08:43 AM
#29
a good healthy 'squirt' of oil, and it does need to spin fast to get an accurate reading.if you're thinking bout selling it, dont do any work, sell it or part it out, you'll be throwing money into something that you'll never be happy with.
Last edited by oldalaskaman; 05-06-2011 at 08:51 AM.
05-06-2011, 09:53 AM
#30
How much oil should be in there? Since the plugs were a little wet, I am assuming there is oil on the rings. I'd hate to put too much and do more damage.
I'd imagine I can check lash, just by pulling the valve covers. Any good write ups on this?
There are photos with the valve covers off and write ups, but I physically don't know where to measure and what tools to use. The basic stuff is obvious once you know it, but you don't what to know how long it took me to find online what piston is #1 and how they are numbered.
It won't start so it can't get warm, and I did indeed fry the starter...
I figure I have another $1,200 in me total but its going to have to run at that point. If I get upside down on it my "investment" privileges will likely be revoked.
I think she's going up on craigslist after work, while I try to figure out the issues.
I'd imagine I can check lash, just by pulling the valve covers. Any good write ups on this?
There are photos with the valve covers off and write ups, but I physically don't know where to measure and what tools to use. The basic stuff is obvious once you know it, but you don't what to know how long it took me to find online what piston is #1 and how they are numbered.
It won't start so it can't get warm, and I did indeed fry the starter...
I figure I have another $1,200 in me total but its going to have to run at that point. If I get upside down on it my "investment" privileges will likely be revoked.
I think she's going up on craigslist after work, while I try to figure out the issues.
This sounds like fried rings, scored cylinders....The compression is wayyy too low.
Only slightly above atmopheric, actually.
This should puff up 150 after 2-3 cycles with the throttle held open.
Its only 9:1 compression in '86. later yr went to 9.5:1
According to the FSM...run 4 cycles, puffs, and min for any cyl is 100psi. They should all be within 70% of each other.
So a good tight motor would be around 150 (stock). this varies with cam timing etc.
BTW
you can buy used engines from $500 to $1500 depending on complete, partial, miles other things. Look around craigslist and flea-bay. Local corvette salvage yard or GM salvage yard.
05-06-2011, 10:01 AM
#31
You can look in the spark plug hole and see if there are scored cylinders and walk away right now if there are. Got a buddy with a cam-scope?
L98 leaking valve seals are as normal as a sunrise. They all leak. kind of a good things too..top end lube at start up.
But with your cyl wet with oil as it sits??? that sounds like burnt motor.Rings seized or stuck in the glans not able to seal the cyl.
Rings can wear and pass a little oil and it will still run, but when the cyl gets deeply scored from trying to seize due to extreme overheat....thats when your compression vanishes on all cylinders.
L98 leaking valve seals are as normal as a sunrise. They all leak. kind of a good things too..top end lube at start up.
But with your cyl wet with oil as it sits??? that sounds like burnt motor.Rings seized or stuck in the glans not able to seal the cyl.
Rings can wear and pass a little oil and it will still run, but when the cyl gets deeply scored from trying to seize due to extreme overheat....thats when your compression vanishes on all cylinders.
05-06-2011, 10:14 AM
#32
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The owner told you that he overheated it and its not been right since?
This sounds like fried rings, scored cylinders....The compression is wayyy too low.
Only slightly above atmopheric, actually.
This should puff up 150 after 2-3 cycles with the throttle held open.
Its only 9:1 compression in '86. later yr went to 9.5:1
According to the FSM...run 4 cycles, puffs, and min for any cyl is 100psi. They should all be within 70% of each other.
So a good tight motor would be around 150 (stock). this varies with cam timing etc.
BTW
you can buy used engines from $500 to $1500 depending on complete, partial, miles other things. Look around craigslist and flea-bay. Local corvette salvage yard or GM salvage yard.
This sounds like fried rings, scored cylinders....The compression is wayyy too low.
Only slightly above atmopheric, actually.
This should puff up 150 after 2-3 cycles with the throttle held open.
Its only 9:1 compression in '86. later yr went to 9.5:1
According to the FSM...run 4 cycles, puffs, and min for any cyl is 100psi. They should all be within 70% of each other.
So a good tight motor would be around 150 (stock). this varies with cam timing etc.
BTW
you can buy used engines from $500 to $1500 depending on complete, partial, miles other things. Look around craigslist and flea-bay. Local corvette salvage yard or GM salvage yard.
Any one have any experiance how much this effects numbers? Now that my starter is fried, I'd hate to get another for naught.
Thanks,
Lucky Kid
05-06-2011, 11:21 AM
#33
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Good morning all--I am brand new to this forum and have been reviewing posts from people with similar issues--ie, an 87 convertible with a "cooked" engine. According to the last owner [friend], the radiator sprung a leak, he tried to refill, then drove until it quit--not good. Input from local Corvette shops and mostly recently, reviews of this forum are not encouraging. I "inherited" the car, so $0s up front. So far, I have been "exploring" and am about ready to remove the heads. Origninal plan was to have some "fun", make a minimal investment, and perhaps make $1-2s on a resale. So far, I am not having much fun! [Wasnt real careful about marking parts or sorting bolts--can I assume the "field manual" will guide a "blind man" back home?]
Figure removing the heads will make the decision on going forward--scored cylinder walls will seal the deal. If so, is there any market for things like tires, wheels, convert top, body panels, etc. At this point, I wouldnt be out for profit--just help out someone with "old car" dreams.
Figure removing the heads will make the decision on going forward--scored cylinder walls will seal the deal. If so, is there any market for things like tires, wheels, convert top, body panels, etc. At this point, I wouldnt be out for profit--just help out someone with "old car" dreams.
05-06-2011, 01:59 PM
#35
Race Director
Good morning all--I am brand new to this forum and have been reviewing posts from people with similar issues--ie, an 87 convertible with a "cooked" engine. According to the last owner [friend], the radiator sprung a leak, he tried to refill, then drove until it quit--not good. Input from local Corvette shops and mostly recently, reviews of this forum are not encouraging. I "inherited" the car, so $0s up front. So far, I have been "exploring" and am about ready to remove the heads. Origninal plan was to have some "fun", make a minimal investment, and perhaps make $1-2s on a resale. So far, I am not having much fun! [Wasnt real careful about marking parts or sorting bolts--can I assume the "field manual" will guide a "blind man" back home?]
Figure removing the heads will make the decision on going forward--scored cylinder walls will seal the deal. If so, is there any market for things like tires, wheels, convert top, body panels, etc. At this point, I wouldnt be out for profit--just help out someone with "old car" dreams.
Figure removing the heads will make the decision on going forward--scored cylinder walls will seal the deal. If so, is there any market for things like tires, wheels, convert top, body panels, etc. At this point, I wouldnt be out for profit--just help out someone with "old car" dreams.
FSM is VERY helpful for those needing help...probably not as much for fasteners though. (I have one an never noticed fastener-type listed.)
05-06-2011, 02:56 PM
#36
See if your local auto parts has a camera to rent. They only cost a couple hundred to buy, so someone has one to use.
A friend used one to spot the crack in his block and did'nt waste 1 minute on rebuilding...replaced the motor because he had the facts.
05-06-2011, 03:25 PM
#37
Race Director
The results are in and....
#1 - 107
#2 - 63
#3 - 54
#4 - 52
#5 - 70
#6 - 54
#7 - 65
#8 - 72
I'm assuming good compression is in the 180-190 PSI range... given 10:1
Didn't need to add oil because there was enough already. Thanks valve seals! Consider the results cold and wet.
I put the plugs back in and tried to start it up and I got one little putter. I kept trying and may have fried the starter motor. After about a minute or two on on and off trying ithe starter just just "clicked". I think I have enough juice with my new 200A starter/charger so the battery is not the issue. The starter is warm to the touch. I just let it be and I'll give it a go in the morning.
None the less I think the motor is %$&#ed!
Has any one heard of a head gasket blowing, losing compression but no coolant in the oil?
I really don't want to pull this beast given a used motor is in the 1.5 to 2K range. I don't want to take the time needed to rebuid the bottom end either.
At this points it might be heads or bust. Unless someone has a lead on a cheap motor...
Any help is greatly appreciated.
Lucky Kid
#1 - 107
#2 - 63
#3 - 54
#4 - 52
#5 - 70
#6 - 54
#7 - 65
#8 - 72
I'm assuming good compression is in the 180-190 PSI range... given 10:1
Didn't need to add oil because there was enough already. Thanks valve seals! Consider the results cold and wet.
I put the plugs back in and tried to start it up and I got one little putter. I kept trying and may have fried the starter motor. After about a minute or two on on and off trying ithe starter just just "clicked"
. I think I have enough juice with my new 200A starter/charger so the battery is not the issue. The starter is warm to the touch. I just let it be and I'll give it a go in the morning.None the less I think the motor is %$&#ed!
Has any one heard of a head gasket blowing, losing compression but no coolant in the oil?
I really don't want to pull this beast given a used motor is in the 1.5 to 2K range. I don't want to take the time needed to rebuid the bottom end either.
At this points it might be heads or bust. Unless someone has a lead on a cheap motor...
Any help is greatly appreciated.
Lucky Kid
05-06-2011, 04:24 PM
#38
Melting Slicks
your compression results aren't very Encouraging. Low across the board! But in order to get a better idea as to were the compressed gas is going, you need to do a cylinder leak down test..
http://www.carcraft.com/techarticles...ter/index.html
now in your case, this will need to be done cold. But at-least you will know were the air is going.
The above article is only one out of many searched hits..
Hope for the best...but be prepaired for the worst.
http://www.carcraft.com/techarticles...ter/index.html
now in your case, this will need to be done cold. But at-least you will know were the air is going.
The above article is only one out of many searched hits..
Hope for the best...but be prepaired for the worst.
05-06-2011, 09:20 PM
#39
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Sold in 2 hours... That was quick!
And I get to keep my "investment privileges"
Thanks everyone for your help! Without it I might have been too far down this rabbit hole to make it out alive.
Maybe I can flip a few more this year and use my "investment proceeds" for a keeper.
I have to say I really started to love the thing. But as they say, it a thin line...
CF you are awesome!
And I get to keep my "investment privileges"
Thanks everyone for your help! Without it I might have been too far down this rabbit hole to make it out alive.
Maybe I can flip a few more this year and use my "investment proceeds" for a keeper.
I have to say I really started to love the thing. But as they say, it a thin line...
CF you are awesome!
05-06-2011, 09:51 PM
#40
Sold in 2 hours... That was quick!
And I get to keep my "investment privileges"
Thanks everyone for your help! Without it I might have been too far down this rabbit hole to make it out alive.
Maybe I can flip a few more this year and use my "investment proceeds" for a keeper.
I have to say I really started to love the thing. But as they say, it a thin line...
CF you are awesome!
And I get to keep my "investment privileges"
Thanks everyone for your help! Without it I might have been too far down this rabbit hole to make it out alive.
Maybe I can flip a few more this year and use my "investment proceeds" for a keeper.
I have to say I really started to love the thing. But as they say, it a thin line...
CF you are awesome!
This one was best to pass on to someone that had the resources to absorb the cost of a major rebuild or replacement. Even if the rest of the car was pristine, a new motor right off the bat is a tough chew...The market is so soft right now (word for worse than sucks?) that you'd never have recovered your investment. (pa-friggin-thetic?)
I got into Datsun Z cars like that. Bought one as a project, ended up with 6 at one time...Sold every one of them after some work for a profit except that first one that threw a rod out the side of the block, (280zx turbo) but got 25% of my money back (after driving it for a year) selling it to "pick-a-part"...lol
Glad you escaped with your credibility. Your investment "partner" will probably reel out a little more rope next time..! Just don't hang yourself!
Good Luck !