how hot until she blows
#21
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The main fan did come on. I don't have another fan that Im aware of. I did replace the thermostat with a new one before we fired it up. It also has new freeze plugs for what thats worth. We made sure it was full of antifreeze before we started it and did use a 50/50 mixture.
So discoloration in the spark plugs indicates piston wear or just a head gasket leak? There is definitely moisture in the oil....it showed over filled only after the break in and there seems to be coolant coming out of the exhaust. We pulled a valve cover also and there is indication of moisture in the cover as well.
Do you think I am looking at another head gasket job? Do you think it was my temp that caused this or some other problem? This sucks.
So discoloration in the spark plugs indicates piston wear or just a head gasket leak? There is definitely moisture in the oil....it showed over filled only after the break in and there seems to be coolant coming out of the exhaust. We pulled a valve cover also and there is indication of moisture in the cover as well.
Do you think I am looking at another head gasket job? Do you think it was my temp that caused this or some other problem? This sucks.
#24
Burning Brakes
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Does the oil look like chocolate milk?If so don't run the engine anymore unless your doing a block test(to see if hydrocarbons are in coolant).If you run the engine with coolant mixed with oil,it can damage all your engine bearings.You may have installed the intake incorrectly causing coolant to leak into engine through the "engine valley".If the block test,tests good(no color change),pull intake & see if anything was installed wrong or theres a crack on/in intake.Once you fix the problem,do a very through coolant flush & flush the engine with a oil flush additive as well.Aluminum engines or headed engines don't handle over heating like a cast iron engine.Keep us updated on what you find
#25
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some of you may throw up a , but my son's 85 hit 296 (dash indicated) due to a water pump failure. new water pump, and she's running okay. ran a compression test, and the readings were around 168, average across 8 cylinders. L98's, at least iron head L98's, are pretty tough little motors.
#26
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Ok gentlemen, I don't mean to jack your thread but maybe one of you could shed some light on this for me...
I believe I have a head gasket leak on an 89 which I suspect got hot at some point (how hot I do not know as I just bought the car but it runs fine, sounds good).
no visible water in the oil, does have visible external coolant leak near the # 7 cylinder...drivers side, near the firewall.
Can any of you tell me approximately how many shop hours I'd be looking at to R&R both head gaskets? I already have a quote for machining & a pretty good feel for parts. Reason being I have a friend who offered to do the reapair for me (very skilled professional mech)- when I asked him what he'd charge, he said it was up to me. I value his friendship so I don't want to cheat him but I tend to be a tightwad hence my delima.
Thoughts?
I believe I have a head gasket leak on an 89 which I suspect got hot at some point (how hot I do not know as I just bought the car but it runs fine, sounds good).
no visible water in the oil, does have visible external coolant leak near the # 7 cylinder...drivers side, near the firewall.
Can any of you tell me approximately how many shop hours I'd be looking at to R&R both head gaskets? I already have a quote for machining & a pretty good feel for parts. Reason being I have a friend who offered to do the reapair for me (very skilled professional mech)- when I asked him what he'd charge, he said it was up to me. I value his friendship so I don't want to cheat him but I tend to be a tightwad hence my delima.
Thoughts?
#27
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Ok gentlemen, I don't mean to jack your thread but maybe one of you could shed some light on this for me...
I believe I have a head gasket leak on an 89 which I suspect got hot at some point (how hot I do not know as I just bought the car but it runs fine, sounds good).
no visible water in the oil, does have visible external coolant leak near the # 7 cylinder...drivers side, near the firewall.
Can any of you tell me approximately how many shop hours I'd be looking at to R&R both head gaskets? I already have a quote for machining & a pretty good feel for parts. Reason being I have a friend who offered to do the reapair for me (very skilled professional mech)- when I asked him what he'd charge, he said it was up to me. I value his friendship so I don't want to cheat him but I tend to be a tightwad hence my delima.
Thoughts?
I believe I have a head gasket leak on an 89 which I suspect got hot at some point (how hot I do not know as I just bought the car but it runs fine, sounds good).
no visible water in the oil, does have visible external coolant leak near the # 7 cylinder...drivers side, near the firewall.
Can any of you tell me approximately how many shop hours I'd be looking at to R&R both head gaskets? I already have a quote for machining & a pretty good feel for parts. Reason being I have a friend who offered to do the reapair for me (very skilled professional mech)- when I asked him what he'd charge, he said it was up to me. I value his friendship so I don't want to cheat him but I tend to be a tightwad hence my delima.
Thoughts?
#28
Race Director
agree with the others, north of 250 is the danger zone. you can fracture the cast top rings and experience oil breakdown. even if you're using redline which could handle the heat the gasket and rings won't. i'm not sure you would really see any skirt or cylinder damage though. cast pistons really don't expand much. if you did it would be from the breakdown in the oil
#30
Race Director
unless you have performed a leakdown it's hard to say 100% the top rings in these old engines are cast iron, not tool steel like many modern motors. they can fracture fairly easy
#31
Le Mans Master
That was like 9 years ago. I think I would know by now if something happened. Absolutely nothing happened to the motor.
#32
Race Director
it's completely possible that nothing happened but only a leakdown will really tell you
#33
Le Mans Master
I've been driving this car for the last 9 years plus. Oil consumption is normal. I have even compression across all 8 cylinders measuring just a few PSI under 200 on all of them and the head gasket is not blown. I have zero coolant loss.
I have fixed more overheated vehicles where I had to replace valves, rebuild/resurface the warped cylinder heads on them, and in some cases even re-ring and hone the bottom end than I can remember at this time. This isn't my first day. I know what happens to motors when they overheat. I've seen it. I've fixed many. Nothing happened to my car which even surprised me. I was only at 280 ish for a short while. When I popped the hood and noticed the fan was not spinning I got back on the open road to force air through the radiator and brought the temps back down quickly. I avoided driving in traffic until I fixed the fan problem.
The OP asked how how till the head gasket blows on these cars. I can't give an exact answer. What I can say is that I hit at least 280 degrees on the guage at least two times on the same day with mine and my head gasket didn't blow nor did my compression readings change or suffered any engine damage.
I have fixed more overheated vehicles where I had to replace valves, rebuild/resurface the warped cylinder heads on them, and in some cases even re-ring and hone the bottom end than I can remember at this time. This isn't my first day. I know what happens to motors when they overheat. I've seen it. I've fixed many. Nothing happened to my car which even surprised me. I was only at 280 ish for a short while. When I popped the hood and noticed the fan was not spinning I got back on the open road to force air through the radiator and brought the temps back down quickly. I avoided driving in traffic until I fixed the fan problem.
The OP asked how how till the head gasket blows on these cars. I can't give an exact answer. What I can say is that I hit at least 280 degrees on the guage at least two times on the same day with mine and my head gasket didn't blow nor did my compression readings change or suffered any engine damage.
Last edited by 86PACER; 03-17-2011 at 11:39 PM.
#34
Racer
Thread Starter
In looking at how to proceed, given that I have antifreeze leaking into the oil.......if I have to yank off the heads again, do I have to get them machined? I was told that is a good idea, but they are brand new. The motor has only been ran for 12 minutes. Opinions?
Also, I have heard of new heads being warped. Apart from this, any thoughts on why a brand new set up would have leaked? We torqued everything to spec...used the right gaskets...etc.
Also, I have heard of new heads being warped. Apart from this, any thoughts on why a brand new set up would have leaked? We torqued everything to spec...used the right gaskets...etc.
#35
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If you have to go to the trouble of pulling the heads you should have them checked for flatness at a shop. Obviously something's wrong with the original repair for it to fail in 12 min, might be that the heads are just fine as they were machined prior to reassembly right? In that case maybe some other reason the gasket did not hold, possibly debris or maybe incorrrect installation or torque sequence...etc.
#36
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The electric fans quit on my 89 once in traffic. I hit 263* before I could breakaway and get air flow. I drove another 2 miles home. Aluminum heads and no damage. It scared the crap out of me when the red warning light lit up. I would not recommend over 245* and only briefly. I hit that few times in traffic in Phoenix in the summer.