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Discussion Starter #1
I am losing coolant from the engine externally. It looks like it is leaking at the very front of the left head, where the head mates to the block, however, it may be coming from further up (such as where the intake manifold coolant crossover joins the cylinder head) and running down and along where the head joins the block, making it look like it is the head gasket that is leaking.


I am not that experienced with this 307 V8. Would those of you that have more years of caring and feeding this engine give me your thoughts, please ? What is the most likely place to experience a coolant leak ? Generally, is the head gasket less likely to be leaking than the intake manifold ?

All thoughts and comments are much appreciated.
 

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94 Fleetwood Brougham
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307's often leaked (well, any Olds V8) from the intake. The "turkey tray" gasket is steel, and can rust over time and leak. Stop leak might help.

It is possible the head gasket is leaking, but I honestly haven't seen many of them, they were always the intake gasket.

I would put some of the pellets that GM used in the 4x00 engines. I think the Golden Seal stuff is rumored to be the same thing. If it works, it just saved you a lot of work....

My Olds 307 (85 Cutlass) factory gasket leaked when my dad had the car, pass side under the AC compressor.
 

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Discussion Starter #3
I have read where GM came out with special replacement intake gasket sets, including special bolts and washers, and detailed instructions for their installation for certain models. Is this the case with the 307, or can you just buy a good name-brand gasket set from NAPA or other quality parts house ?

I will probably replace the intake gasket, and while I have access, do the valve covers, and replace a leaking power steering high pressure hose.
 

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Remember GM didn't use gaskets on the valve covers, but most gorilla mechanics were clueless to that and put them in and cranked them down anyway. They used RTV, and there is little small tangs that you torque very gently down to that provide the proper clearance for the RTV to seal. Mine were leak free, but you need to follow the instructions on the RTV (I used Ultra Grey) carfully to ensure a leak free seal.

I would go for new intake gasket. A godo time to install a Torque Plus gasket if they are still made. I did them on my 80 T/A with 455 and they were better in the low end and cold starts. They have a screen over the intake port, provides some additional breakage of the A/F mix, helps a lot when cold, providing (so they say) better atomization of the fuel, for better fuel economy and power. Yes, it can restrict top end, but tell me, who tops ends out a 307? It isn't worth trying....

Just a thought to do while you are in there...
 

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90 Brougham 5.7, 05 Deville DTS
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ralphb said:
I am losing coolant from the engine externally. It looks like it is leaking at the very front of the left head, where the head mates to the block, however, it may be coming from further up (such as where the intake manifold coolant crossover joins the cylinder head) and running down and along where the head joins the block, making it look like it is the head gasket that is leaking.


I am not that experienced with this 307 V8. Would those of you that have more years of caring and feeding this engine give me your thoughts, please ? What is the most likely place to experience a coolant leak ? Generally, is the head gasket less likely to be leaking than the intake manifold ?

All thoughts and comments are much appreciated.
Don't feel bad, my 89 Brougham is leaking water from the same damn spot. From the help I have recieved through this board, my mechanic's visual diagnostics, it seems to be the intake manifold gaskets took a shit.

I tried the bars leak--golden seal, and it didn't do much. I guess the gasket is that shot.

I priced the intake manifold gasket kit from the Cadillac dealer and my cost is ~$80, this is to give you an idea of what the gaskets cost.

Good luck fixing your problem, and let us know what happens.
 

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90 Brougham 5.7, 05 Deville DTS
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AElayyat said:
Don't feel bad, my 89 Brougham is leaking water from the same damn spot. From the help I have recieved through this board, my mechanic's visual diagnostics, it seems to be the intake manifold gaskets took a shit.

I tried the bars leak--golden seal, and it didn't do much. I guess the gasket is that shot.

I priced the intake manifold gasket kit from the Cadillac dealer and my cost is ~$80, this is to give you an idea of what the gaskets cost.

Good luck fixing your problem, and let us know what happens.
*UPDATE*
I took my car (89 Brougham) to the Caddy dealer Monday and it turns out that it is the intake manifold gaskets. The dealer should have the car done some time tommorow or Friday at the latest. I don't know what kind of numbers I'm looking at yet, so keep your fingers crossed guys.
 

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Discussion Starter #7
Let's see who can come the closest to guessing what AElayyat's job is going to cost - just for fun. I say $650 .

I am doing the same job myself. I will report in when I get it back in running condition again.
 

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'80 Fleetwood Coupe, 1994 and 1995 Mercedes 140 Coupe
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Where the heck were you guys when I was in the business??? $$$$$$???
 

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ralphb said:
Let's see who can come the closest to guessing what AElayyat's job is going to cost - just for fun. I say $650 .

I am doing the same job myself. I will report in when I get it back in running condition again.
$650 - Close but no cigar.
Try again.
 

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01 STS, 92 Roadmaster, 01 SLS-sold, 88 Brougham-crushed
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holy crap!!!!! i replaced my own intake manifold gasket when i did my cam swap. and the gasket itself was less than $20. plus some rtv sealant.
 

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Olds 307's are noted to rust out the valley pan intake gasket. I changed mine about a year ago. It's a pretty major job to remove all the accessories to get to the intake. Remember to buy and use a tube of 3M yellow gasket glue to hold the end gaskets in place. This should solve your problem
 
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