C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

c4 major coolant leak!

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Old Oct 29, 2009 | 03:46 AM
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Default c4 major coolant leak!

I just "found" a C4 corvette in the old mans garage, not been run for 4 years. I fired it up but it smelled like it was getting hot so shut it off, realised it was low on water i filled up the radiator and run it again down the road but it started spewing water out from underneath so i took it straight back before it got hot. Now as soon as i fill it up with water it pours straight out from underneath, from the back of the engine just above the fly wheel i think but i can't get to it and i have limited experience with these things! Any ideas?
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Old Oct 29, 2009 | 04:08 AM
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Head gasket would be first thought, without looking it over based on your description.
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Old Oct 29, 2009 | 04:24 AM
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Rear freeze plugs. That would require removal of the trans. There are two in the back of the block up high, hidden by the trans case.


Last edited by 86PACER; Oct 29, 2009 at 04:37 AM.
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Old Oct 29, 2009 | 04:31 AM
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Welch plug mate, the coolant probably ate through them while it sat still all that time.
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Old Oct 29, 2009 | 04:39 AM
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[QUOTE=86PACER;1571976541]Rear freeze plugs. That would require removal of the trans. There are two in the back of the block up high, hidden by the trans case.

yes someone else suggested this, i checked the t-stat which was corroded and stuck also, i think maybe it got a little warm and the pressure will have popped the rusty plug out maybe does this sound right? is it major work to replace these?
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Old Oct 29, 2009 | 04:43 AM
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Originally Posted by 86PACER
is it major work to replace these?
The plugs themselves are simply tapped in flush with a socket and hammer. The problem is you can't get to them without taking out the transmission first. You have the torque converter, flywheel, and trans in the way.
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Old Oct 29, 2009 | 04:50 AM
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Its not a hard job if youve got the tools and the skill to do it.
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Old Oct 29, 2009 | 04:59 AM
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Originally Posted by Casethecorvetteman
Its not a hard job if youve got the tools and the skill to do it.

ha ha, i can buy the tools . . . ! ?

as for the skill, i'd better call around and get a quote! Thanks
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Old Oct 29, 2009 | 07:54 AM
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i hope that the plug wasnt forced out by ice.chances are there will be more damage.
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Old Oct 29, 2009 | 08:13 AM
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Originally Posted by c-4 lhozwalte
i hope that the plug wasnt forced out by ice.chances are there will be more damage.
Possibly. Suggest you do a lot more looking before you even think about spending money. If the freeze plug is bad it is very likely the remainder are not far behind.
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Old Oct 29, 2009 | 08:36 AM
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What year ?? If an LT1 engine there is the cross-over tubing between the two heads above the bell housing?

Joe
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Old Oct 29, 2009 | 08:45 AM
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Originally Posted by devildog
What year ?? If an LT1 engine there is the cross-over tubing between the two heads above the bell housing?

Joe
the car has been in spain for 4 years so should not have been subjected to frost. I'm not sure what engine it is but it has the big grey airbox on the top with "cross fire injection" written on it and air intakes on either side staggered. Hope this helps, thanks!
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Old Oct 29, 2009 | 08:46 AM
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it is a 1986
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Old Oct 29, 2009 | 09:13 AM
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If your lucky, it could be a coolant hose from the oil cooler, if it has that option.
You need to have a better look.
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Old Oct 29, 2009 | 09:17 AM
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Originally Posted by MadMatty
it is a 1986
Not with a grey air box showing Cross Fire Injection It's an 84.
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Old Oct 29, 2009 | 09:21 AM
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Originally Posted by MadMatty
I'm not sure what engine it is but it has the big grey airbox on the top with "cross fire injection" written on it and air intakes on either side staggered. Hope this helps, thanks!
Originally Posted by MadMatty
it is a 1986
1986???

The Crossfire was only used in the 1984 for C4s and 1982 in the C3.

RACE ON!!!
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Old Oct 29, 2009 | 09:39 AM
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Originally Posted by MadMatty
I just "found" a C4 corvette in the old mans garage, not been run for 4 years.
How do you lose/forget about a Corvette in the garage? Pics?
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To c4 major coolant leak!

Old Oct 29, 2009 | 10:34 AM
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Originally Posted by rickreeves1
How do you lose/forget about a Corvette in the garage? Pics?
I bought a C5 several years ago, then the C6 Z06, he was trying to compete so he picked up an old c4 ! He has 12 old cars in spain, mostly old british classic sports cars such as MG's and triumphs etc, all mechanicaly ok but not been run - i thought i'd try help him out by taking the 'vette off his hands and shipping it back to the UK as a little project over winter - i don't mind "bolting on" new accessories and doing the easy bits but didn't expect this! It Must be an 84, is the cross fire injection a good engine or is it old technology compared to the LT1 ?
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Old Oct 29, 2009 | 10:36 AM
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I had a similar issue with my 86. Don't know if yours is an 86, or an 84, but, mine has this little pipe on the passenger side of the distributor cap, with a rubber hose that i had to remove to get at the distributor hold down bolt. sometimes i forget to put it back and the back of my engine spews coolant. Might be worth taking a look. Good luck.


Mike
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Old Oct 29, 2009 | 01:06 PM
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Originally Posted by MadMatty
I just "found" a C4 corvette in the old mans garage, not been run for 4 years. I fired it up but it smelled like it was getting hot so shut it off, realised it was low on water i filled up the radiator and run it again down the road but it started spewing water out from underneath so i took it straight back before it got hot. Now as soon as i fill it up with water it pours straight out from underneath, from the back of the engine just above the fly wheel i think but i can't get to it and i have limited experience with these things! Any ideas?
Have the vehicle towed to a knowledgable repair shop.Have them pressure test cooling system to pinpoint leak if you are not sure of leak location.If it is from frost plugs behind transmission decide if its worth fixing.1982 corvettes are worth more than the 1984s.Also if it is leaking from frost plugs & car has been sitting for years it may have other issues that need to be fixed(seals leaking,brake work,possible mouse infestation,transmission or differential problems,paint fading,interior problems,or electrical issues).If car is a 1984,in poor condition & has no sentimental value to you it would be best to part-out vehicle due to the fact fixing these issues will cost alot more than car is worth,especially buying parts in Europe.
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