Overheating and venting oil

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philthehill
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Re: Overheating and venting oil

Post by philthehill »

I would suggest that the first thing to be investigated is the oil separator attached to the front valve chest cover to ensure that it is clear. If that is blocked the engine crankcase cannot vent and pressure will build up in the crankcase pushing oil out of the rear scroll/bearing which will make its way to the outside of the gearbox. Oil can be seen as an oil blob on the gearbox drain plug and oil wash on the gearbox casing.
Check that you have the right oil filler cap. With the oil separator canister you should have the vented cap.
Looking at the picture of the engine bay the engine and ancillaries are made up of a mis-match of parts.
Your coil mount bracket nut needs to be tightened and the top hose needs to be replaced. You appear to have the wrong thermostat housing which does not help the top hose.

TimM
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Re: Overheating and venting oil

Post by TimM »

Thanks again and here's what I know...I have written the answers next to most of the questions.

1) Why was the work done? Presumably the exhaust had blue smoke when the engine was running and possibly a high oil consumption? Yes, that's right!
2) The brakes seem OK but they were very worn and have had the the shoes replaced since owning the car and have done very few miles.
3) Is performance of the car generally good? Yes, lovely to potter about in, all fine.
4) What sort of mpg are you getting? I am not sure, but it seems OK.
5) What's the history of this - how long have you owned the car - was it running well and then the faults developed, or was the work done for a previous owner and the car has had the current fault since you bought it? The history is a bit of a mystery. I have only owned it for a couple of years. I bought from a canny but elderly man who spoke about the engine being a replacement and very worn, but i didn't know anything else. The problems came after my ownership but I think he (the old man) swapped out the engine prior to selling it to me,

As an aside, when the 1098 was fitted, were the gearbox and back axle changed as well, and were the front brakes uprated? To check this:
a) Is the gearbox ribbed or does it have a smooth case? It has a smooth case.
b) Does the back axle have a drain plug in the centre and a filler plug near the top of the rear, or is the filler in the nose of the diff, near the prop shaft?
c) Is the diameter of the front brake drums 7 inches or 8 inches? I don't know about the brakes, but the drain plugis in the centre and the filler is near the prop.

TimM
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Re: Overheating and venting oil

Post by TimM »

The filler cap is vented. The DIY compression test showed that the draw from the engine doesn't change when the engine is being revved.
mowogg
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Re: Overheating and venting oil

Post by mowogg »

I would be suprised if the air breathing set up will work. The symptoms you describe align with too much pressure in the engine.

Systems with canister breathes either go directly to the carb or pcv on very late models. In either case the system has significant pressure to keep a partial vacuum through the canister

I don't see how pluming the canister to the inlet of the air filter will get anywhere close to this. Without sufficnrt vacuum pressure will build in thr engine and leave via the scroll seal at the back.

Suggest you modify the set up to a standard set up. Either change carb with vacuum inlet or change canister for earlier pipe set up and change the rocker cover and air filter.
kevin s
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Re: Overheating and venting oil

Post by kevin s »

Ours is a 69 one and the pipe goes into the back of the air cleaner so functionaly the same as this.

rps20210808_180304.jpg
rps20210808_180304.jpg (111.89 KiB) Viewed 285 times
As has been suggested above I would start with taking the breather can off and checking it flows air freely. As a very simple test you could even put a clean length of hose on it in situ and see if you can blow through it (with the engine off)
TimM
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Re: Overheating and venting oil

Post by TimM »

Brilliant, thanks guys. I will try that later today. :D
TimM
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Re: Overheating and venting oil

Post by TimM »

OK, so air is going into the engine OK, but there is some slight resistance. Sorry to be so useless but before I order parts (wrongly) could someone point me in the direction of the bits I need. I would like yo keep the carb the same , primarily as its working fine and the cost. So I need...

Early rocker cover with hose setup to...
Air filter?

Thanks again...feeling optimistic!
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