1999 Suburban Coolant Leak

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Carl - 21 Jan 2007 17:08 GMT

Hi everyone,

99 Suburban with 350/FI and 127K miles. Noticed a small oscillation in
the temperature gauge about 2 mo ago, then one episode of spontaneous
temps 220+ with loss of coolant. Now I have developed an external leak
that appears to originate at the front of the passenger cylinder
head-to-block interface. No CELs lit. No white smoke in exhaust, engine
runs fine.

Any method of confirming this is the problem before comencing to pull
the cylinder head? Is this a common problem during these model years
with higher mileage?

Thanks for your time,

Carl

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shiden_kai - 21 Jan 2007 18:38 GMT

> Any method of confirming this is the problem before comencing to pull
> the cylinder head? Is this a common problem during these model years
> with higher mileage?

I'd be very surprised if it's the cylinder head gasket. The intake
manifold gaskets are what is the common failure on these engines.

Ian

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Hal - 22 Jan 2007 05:19 GMT

> 99 Suburban with 350/FI and 127K miles. Noticed a small oscillation in
> the temperature gauge about 2 mo ago, then one episode of spontaneous
[quoted text clipped - 6 lines]
> the cylinder head? Is this a common problem during these model years
> with higher mileage?

Most likely it is the intake manifold gasket and not the head gasket.
Expect to see some slight surface damage to the intake manifold/head
casting where the leak was occurring. You can use black RTV to fill in
the rough spots when you install the new gaskets. It's not a terribly
hard job to do on this vehicle.

Chris

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