Mocha-Latte milkshake from somewhere... :(
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Melting Slicks
Joined: May 2007
Posts: 2,382
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From: Kathleen FL
Mocha-Latte milkshake from somewhere... :(
So this is gonna be the second time that the intake would be off the 88 because of a dreaded coolant leak somewhere as well. It also has the mysterious disappearing coolant syndrome. Every now and then that low coolant light would come on. I'd let it cool down and check the coolant in the radiator and it wouldn't be up to the top anymore after numerous topping off. I confirmed that my head gaskets are ok since all cylinders hold pressure. All cylinders tested for 170 psi + or - 5 psi for "longer than I can sit and wait for it to bleed off." So what could this be here? Yes, it sucks to have 2 Vettes that don't run for the time being... 
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Joined: Sep 2000
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From: The Top of Utah
I wouldn't rule out the head gaskets so quickly. You would hate to R&R the intake, only to find you hadn't cured the problem. A running engine builds a lot more than 170# of cylinder pressure. Besides, is it the cylinder that holds the pressure so long? Or the capture feature of the gauge? Water that "disappears" most often escapes through the exhaust, unnoticed. It can come from several places, intake gasket, head gasket, cracked head, cracked block... Unless you have clear and convincing evidence of where it is coming from, I think a test for CO in the coolant would be worth while.
RACE ON!!!
RACE ON!!!
Team Owner
Joined: Aug 2000
Posts: 40,156
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From: San Pedro CA
I wouldn't rule out the head gaskets so quickly. You would hate to R&R the intake, only to find you hadn't cured the problem. A running engine builds a lot more than 170# of cylinder pressure. Besides, is it the cylinder that holds the pressure so long? Or the capture feature of the gauge? Water that "disappears" most often escapes through the exhaust, unnoticed. It can come from several places, intake gasket, head gasket, cracked head, cracked block... Unless you have clear and convincing evidence of where it is coming from, I think a test for CO in the coolant would be worth while.
RACE ON!!!
RACE ON!!!
Lisle makes a kit to test for exhaust gasses in the coolant. It's a very accurate test.
Race Director
Joined: May 2006
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From: Phoenix Arizona
Almost guarantee a head gasket leak. Things change dramatically when alluminum heads heat up on an iron block. An intake gasket will usually leak into the oil, or at least somewhere you can see it. The radiator isn't wet is it? Plastic radiators dend to leak when they cool down, not when they're hot. Also check for seapage at the water pump, it can be very difficult to spot because it blows off and evaporates on the hot engine. Although reading your post versus the title is some what confusing (to me). Do you have coolant in the oil, or are you just losing coolant?
Last edited by zr1fred; Dec 6, 2007 at 01:04 PM.
Melting Slicks
Joined: May 2000
Posts: 2,029
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You talked about mocha-latte in the subject but then only about disappearing coolant? Well, if its mocha-time then don't read further but if you only are missing some coolant then my experience might apply.
I blew a head gasket few years back and we did a whole top end rebuild on my motor. Well, everything went well and my car worked perfectly except the fact that I slowly lost some coolant. No mocha or anything obvious like that.
Well, in the end I did find the problem. My base plate was leaking from driver side rear corner. We took it all off and redid it. The problem was that there is several lengths of intake bolts. FSM doesn't say anything about where which one goes. When I measured them I found there was some that at quick glance looked the same were actually a tiny bit longer than others. The difference was maybe just 0.04-0.08" but when these longer bolts were placed in the rear corner of the base plate they bottomed out and it looked perfect in my torq wrench but in fact the base plate was not torqued down at all in the corner. This was visible when the engine was warm. Coolant bubled out from the rear corner when watched closely.
So, be careful with them bolts
I blew a head gasket few years back and we did a whole top end rebuild on my motor. Well, everything went well and my car worked perfectly except the fact that I slowly lost some coolant. No mocha or anything obvious like that.
Well, in the end I did find the problem. My base plate was leaking from driver side rear corner. We took it all off and redid it. The problem was that there is several lengths of intake bolts. FSM doesn't say anything about where which one goes. When I measured them I found there was some that at quick glance looked the same were actually a tiny bit longer than others. The difference was maybe just 0.04-0.08" but when these longer bolts were placed in the rear corner of the base plate they bottomed out and it looked perfect in my torq wrench but in fact the base plate was not torqued down at all in the corner. This was visible when the engine was warm. Coolant bubled out from the rear corner when watched closely.
So, be careful with them bolts
Thread Starter
Melting Slicks
Joined: May 2007
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From: Kathleen FL
There is no white smoke during cold and hot starts. When the car is at a prolonged hot idle coolant about 200 deg., there comes very faint amount of white smoke, not much. Definitely smells like coolant though. And I know the car isn't overheating because 190-200 deg coolant temps are normal range. Last time I pressure tested the cooling system, there was a slight leakdown in the pressure. You can hear a slight fizzing noise from the front, near the water neck. Cranking pressure is and was always in the 170s and no my guage is not the "capture feature type." Holds the pressure there indefinitely. Since the intake is off again, I'm gonna have my dad test it for warpage. I'm beginning to think I have a warped intake. Hopefully that's not too hard to fix...
Thread Starter
Melting Slicks
Joined: May 2007
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From: Kathleen FL
Final conclusion:
Intake manifold wasn't seating properly. It was actually seated on a piece of old broken intake gasket stuck to the head DOOOOHHHH!!!!!!!! I was too blind to notice that before. It pays to work on these cars when you have ample light all around you. One overhead 60W light bulb in a car garage isn't enough. So thanks everyone for chiming in!
Intake manifold wasn't seating properly. It was actually seated on a piece of old broken intake gasket stuck to the head DOOOOHHHH!!!!!!!! I was too blind to notice that before. It pays to work on these cars when you have ample light all around you. One overhead 60W light bulb in a car garage isn't enough. So thanks everyone for chiming in!
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Incidentally, my head gasket problem manifested itself only with some coolant loss and bubbles in the coolant (plus some weird smoke in the expansion tank). However, the compression test was good, and the 'coolant pressure' test was good too. It was only after I removed the head that I saw #8 was leaking across the gasket.
I think a Block Test would have been a clear indication of my head gasket problem.
I think a Block Test would have been a clear indication of my head gasket problem.
Thread Starter
Melting Slicks
Joined: May 2007
Posts: 2,382
Likes: 2
From: Kathleen FL
Incidentally, my head gasket problem manifested itself only with some coolant loss and bubbles in the coolant (plus some weird smoke in the expansion tank). However, the compression test was good, and the 'coolant pressure' test was good too. It was only after I removed the head that I saw #8 was leaking across the gasket.
I think a Block Test would have been a clear indication of my head gasket problem.
I think a Block Test would have been a clear indication of my head gasket problem.