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'81 Dry Sump - coolant in oil - Page 2 - Engine/Ancilliaries - The Lotus Forums #ForTheOwners Jump to content


'81 Dry Sump - coolant in oil


Steve4012

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When I used Daves calibration kit I found on one carb practically no fuel from the pump jets and lots from the other. My car stunk of fuel when the pump jets were off setting. I know the smell was from the carbs because I tested everything else including the tanks and vents. Now the pump jets are calibrated, no fuel smell! Make sure the pump jet springs are on the correct way round. They are conical and if inverted the pump jet may not work!

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The oil analysis came back as fuel contaminated rather than coolant so that's good news. The oil has a dilution of 4.36% with an acceptable limit of 4% so a fraction over but with 0 miles all should be fine internally especially as the oil pressure was just lower than I'm used to seeing rather than none at all. I believe it was the many times over starting and driving 30 yards to test my handbrake adjustments that have caused this along with some fueling issues. I've always used .45 idle jets so I'm going revert to either standard .40 or .42 and see how it runs. Looking forward to using Dave's @LOTUSMAN33 test rig for pump jet calibration and see if these are supplying excessive fuel. I've changed the oil once already but even this new oil has turned black straight away so I'm going to change it again once the fueling is sorted. One problem with the dry sump is that you have to run the car for the oil tank to fill before this oil can then be drained from the tank and this seems to leave a fair bit of oil unchanged. I'm thinking of disconnecting the main oil return pipe to the engine from the tank so I don't have to start the car and this will hopefully remove more oil. Has anyone tried this before on a dry sump?

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Float heights: how does everyone set these? Simply set to 14.5 - 15mm measuring between float and gasket held vertically as per the manual or then go on to use the sideways technology method of measuring 27mm from top of fuel stack to fuel level in the bowls?

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Never heard of measuring fuel height. This is not mentioned in the font of knowledge about Dellortos namely the Des Hammill book.

How would you measure the fuel level anyway without taking off the top which would make the level change without displacement from the floats?

On the dry sump there should not be a lot of oil left in, if you drain it immediately after switching off, as there isnt any sump at all on these cars. There may be some in the return hose but on all cars there is probably a fair bit more left in the oil cooler and its hoses when draining.

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Link makes no sense to me. The presence of the floats in the top of the fuel will cause the level to rise when the top is back on.

He mentions the adjustment could be done another way with the top on, or with the top off. But the two methods would give completely different results.

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Well I took mine apart to have a look. The fuel level was 30 mm as measured on that video. I adjusted the float height as it may have been a little off spec. Is it possible the excess fuel in your oil is being caused by the needle valve not seating correctly and nothing to do with the float height?

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It's possible Fabian. The needle valves were replaced about 18 months ago and look OK with no obvious groove where they seat. They move freely on the float pivot as well. Once back together I'll switch the fuel pump on and check inside the main barrels of the carbs for any drips with the plenum off.

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  • 5 months later...

6 months later and realised I neglected to update ths thread. The oil analysis showing no coolant in oil was great news, I put the car back to standard .40 idle jets and got the car running really nicely. I've done over 1000 miles between MOT's which is way more than I normally do and really enjoyed using the car a lot late summer/autumn. I'm now forcibly off work again (Covid) so thought I'd get a task done that's been niggling me. I should have put a new gearbox input shaft in the car when I had it all apart a couple of years ago but didn't and my one was a bit worn on the splines. Not bad but not great either. So I've ordered a new one and have started getting ready for gearbox off. One of the items that has to come off is the turbo oil drain pipe and on the dry sump that means all the engine oil will exit the engine! No problem, new oil and filter won't hurt as it's been about 700 miles. I have found though that the oil looks a lot older than the 6 months and 700 miles it actually is. It looks mid brown colour like cold coffee and still has a hint of fuel smell which surprised me with standard idle jets and the idle screws set to a fairly standard 3 full turns out. Need to check @Lotusfabsuggestion again about the needle valves seating correctly as I really want the oil to stay in a healthier state for a relatively short time/ mileage. Will post back...

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