Chevy technical questions...

[Camaro91]

Hi all, I have a 1981 Caprice Classic with the 305, right-hand drive converted. I have a few technical questions that I'm looking for assistance with - any help would be much appreciated.

1) The engine was rebuilt before I got the car but ran low on oil due to a leaking oil pressure sender. Now at idle there is a distinctive 'whirring' from the rocker cover of the right-hand bank (looking toward the rear of the car). This dissapears above idle but when the engine is under load (ie. in gear) and accelerating there is a loud tapping noise from the same side of the engine. What might have happened and is there a way to remedy it?

2) When I turn off the windscreen wipers they stay on for a good few minutes. Could this be a sticking relay, and where are the relays located?

3) At above 60mph the speedo jumps to higher speeds and makes a whirring sound.

4) The fuel pressure gauge moves quickly with the fuel in the tank. I assume this should be damped, is there a fix for this?

Apart from that it's in OK condition and if I can sort these items it will be pretty much good to go so all help is gratefully recieved.

Thanks,
Matthew

[Camaro]

Answer to number 4)

Fuel tanks in these things are notorious for not being baffled, from memory the harder the accelerate, the more fuel you have!

Unless you pull the tank, split it open and baffle if, I don't think there is a lot you can do.

[Camaro91]

I think I'll live with the wavy pointer on the fuel gauge then thanks! I can get a decent reading if I'm parked flat so I'll just remember to check it when I set off

[ian_uk1975]

Knocking under load, especially in view of the engine previously running low on oil, sounds like worn rod or mains bearings. If so, you're looking at another rebuild. What's your oil pressure at idle and what was it before running low on oil?

[LuS1fer]

If it has air con, disconnect the belt and see if it still knocks as that can echo through the block. had it on my Z28.

For the speedo, check the cable as these can fray. I assume it is mechanical at that age. A new one may solve it assuming it hasn't knackered the gauge.

[Chevy305]

ian_uk1975 said:

Knocking under load, especially in view of the engine previously running low on oil, sounds like worn rod or mains bearings. If so, you're looking at another rebuild. What's your oil pressure at idle and what was it before running low on oil?

Hi Ian,

I didn't get any oil pressure warnings before or after. I would say the oil level would have been just on the 'minimum' mark on the dipstick when I noticed. The noise is like a tinny clatter, I showed my friend a video of it and he said it sounds more like an exhaust leak but we'll have a look tonight and hopefully it's the case!

I don't have air con on my model but I'll look into the speedo cable.

Thanks, Matthew

[Matt Harper]

Might sound a bit of a daft question, but you are sure it's not just pinking, (predet) right?

Also (for process of elimination) check tightness of exhaust manifold on the affected side.

Assuming it's neither of the above, I tend to agree with the rod-bearing (little end) failure hypothesis - but a bit hard to be emphatic with just a written description.

Long-shot, but does the car have a magnetized sump-plug? Either way, drop the engine oil and look for any metallic debris that would indicate a rod bearing collapse.

[Captain Cadillac]

Wipers are probably down to a bad switch.

A Caprice without AC? Odd.

If the motor is shot, remember that a more powerful crate 350 can often be had for as much as its going to cost to have your engine rebuilt.

[Chevy305]

Matt Harper said:

Also (for process of elimination) check tightness of exhaust manifold on the affected side.

... found it. Exhaust leak! (Phew).

Thanks for the comments chaps. I'll have a look at that switch & speedo cable.

Cheers, Matthew

[ian_uk1975]

Glad it's just an exhaust leak

Best case scenario!

[chevy-stu]

I can highly recommend the copper exhaust gaskets. I was constantly blowing mine, even the 'heavy duty performance' ones. .

[Chevy305]

Thanks mate, I will check them out, it's patched up at the moment temporarily. There are still a few jobs to do but I'm getting there - wiper switch needs replacing, speedometer still to fix (clicking and needle waving), needs two new doors and a respray. Mechanically though it's sound, runs perfect