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Old 06-06-2019, 08:59 PM   #1
tucsonjwt
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Coolant temp sensor and exhaust manifold gasket interference

I plan to replace the temp sensor on my 83 C20 454 but I have some interference from the exhaust manifold gasket (on the driver's side.) This is a
Goodwrench remanufactured engine, so I guess whatever company did the rebuild for GM was a little sloppy with the gasket install. Before I start hacking away at that gasket, does anybody have any advice on the best way to cut away the part of the gasket that is in the way of the sensor removal? I don't want to create a bigger problem for myself.

Also, do I need to drain out some coolant prior to the sensor removal?

I have a new connector with lead wire on order to replace the damaged one in the pic.
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Old 06-06-2019, 09:55 PM   #2
mongocanfly
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Re: Coolant temp sensor and exhaust manifold gasket interference

that visible gasket isn't doing a thing but taking up space...trimming it out of the way wont cause any issues
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Old 06-07-2019, 10:54 AM   #3
sweetk30
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Re: Coolant temp sensor and exhaust manifold gasket interference

cut area with good pair of side cutters .

drain some coolant or be super fast at the removal and install and spill some .

more important tho is that casting flashing or a crack started on the exhaust manifold just behind the port in front of the sensor ? reason i ask is original bbc manifolds are known to crack .
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Old 06-07-2019, 12:51 PM   #4
95 S_Trucker
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Re: Coolant temp sensor and exhaust manifold gasket interference

And that gasket was put on by whoever put the manifold on, not the engine manufacturer.
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Old 06-07-2019, 02:25 PM   #5
tucsonjwt
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Re: Coolant temp sensor and exhaust manifold gasket interference

Yes, I was not thinking about how the engine would be shipped by the rebuild factory.
According to the previous owner, a Chevy dealer installed the reman engine and SM 465 transmission. I don't understand how an exhaust manifold gasket can be installed that far off without it being noticed.

I do notice some exhaust noise somewhere toward the front of the truck, but
I am reluctant to mess with the manifolds because of all the smog tubes which look somewhat fragile to me. I have to keep the smog equipment intact to pass annual emissions in AZ. I just went out and ran the truck and put my hand and a piece of paper near the exhaust manifold in the area you mentioned, but there does not seem to be a leak there. I know idle speed is not a good test, but it seems to be ok. I threw some water on that area and I think what you see may just be a mold mark showing.

I know GM BB exhaust manifolds (as well as Ford 460 manifolds) are prone to cracks, but mine appear to be in good shape, probably due to the dry climate of southern AZ and no rust from salt on the roads.

Thanks to all for the info. When I get the new connector and lead I will give it a go, after I drain out some coolant, since i don't want to have to be quick on the sensor install and risk cross threading it.
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