Changing manifold gasket?
Thread Starter
Pro
Joined: May 2013
Posts: 570
Likes: 22
Changing manifold gasket?
i think I have an oil leak coming from the back side of my manifold gasket. I have noticed oil on on the back side top of the engine near the firewall.
How do do I confirm the source of the oil? If it is the manifold. Is the gasket difficult to change? It’s on a 1969 427 L68.
How do do I confirm the source of the oil? If it is the manifold. Is the gasket difficult to change? It’s on a 1969 427 L68.
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
The local auto parts store should have a kit with dye. Put the dye in the oil. The kit comes with a light to find the leak. The leak will be visible with the light.
Changing the gasket isn't that hard but the cooling system has to be drained.
Craig
Changing the gasket isn't that hard but the cooling system has to be drained.
Craig
Last edited by Street Rat; May 2, 2018 at 09:23 AM.
Thread Starter
Pro
Joined: May 2013
Posts: 570
Likes: 22
will the silicone prevent a leak? Wasn’t sure how much pressure gets built up where the intake manifold meets the engine block.
Thread Starter
Pro
Joined: May 2013
Posts: 570
Likes: 22
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Race Director
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From: Charlotte NC
Actually there is always positive pressure. The is no way the rings on the pistons are 100% efficient and not having blow by.
So...depending on how bad the engine is in regards to the blow by...IF the PCV can actually keep up with the positive pressure and make it a negative pressure...you should not worry.
One way to tell is to pull out your fresh air tube in the passenger valve cover and crank teh engine and put a dollar bill over the grommet. IF the dollar bill gets sucked to the grommet and when you go to slide the dollar bill off it...it is held there with tension. Your PVC is able to make this negative pressure....which is what you want.
IF the dollar bill gets blow away from the grommet and when you place your hand over the grommet you feel puffs of air...THAT is not good.
Keep in mind that the engine needs to be sealed up and no major areas for air to get into the engine. So...a bad gasket on an oil fill cap ...can allow air to be drawn into the engine and it is NOT filtered...a bad gasket on your oil dipstick... SO...just because the dollar bill did not get sucked to the grommet does not mean you have a problem becasue you have to make sure the engine is sealed up.
DUB