Lotus Elan

Engine.....

PostPost by: Type28 » Thu Dec 31, 2015 7:16 pm

Hi Group

Since purchasing my Elan I have had a few issues, but over the year I have owned it,it has been great fun.
I bought the car to be a good useable car that I wouldn't have to worry about leaving in hotel car parks and wouldn't have a compulsion to clean it after every use or check the weather forecast before I went out in it!
Anyway the engine has developed a little knock on start up it only last two or three seconds until the oil pressure gauge rises to around 40 PSI and it won't do it again until the car has sat for a day. I changed the oil pump encase the valve was sticking and allowing the oil to drain into the sump, but that didn't have any effect.
The cylinder head has been converted to unleaded by the previous owner, and I never really felt the car pulled as well as it should have the car starts, runs fine, no smoke, but it feels flat, so, thinking that I may have to change the crankshaft bearings I thought I would do a compression test. With the engine hot and throttle fully open the readings are 150,150,155&150 all with in 20 PSI, but below the recommended 170 for a sprint engine. I have read through some of the paperwork that came with the car and I suspect the new valve seats may not have been that well fitted, so I think that at the start of the new year I will be removing the engine.
question to the forum am I being two pessimistic ? The car runs fine and handles like a dream?
O' and a happy new year to all!

George
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PostPost by: bill308 » Thu Dec 31, 2015 8:50 pm

Hi George.

A couple of things you might want to consider:

1. Are the compression readings hot or cold?
2. How much confidence do you have in the gauge? Do you have access to another one, to compare readings?
3. Power readings can be affected by a number of things. Can you confirm ignition timing is correct throughout the rev range and is it changing smoothly?
4. Does it feel down on power throughout the operating range or only within certain bands or under a particular loading?
5. What fuel are you running and do you have air any air/fuel data?

Bill
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PostPost by: Elanconvert » Fri Jan 01, 2016 9:38 am

hi george
any 'knock' would worry me, but if oil cures it, then not terminal - yet.....
if you want to run it for a while, it might be worth spending ?100 on a reputable rolling road fettle......
what grade oil are you using?

:D fred :D
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PostPost by: john.p.clegg » Fri Jan 01, 2016 3:51 pm

If I had an engine with a knock,the last thing I'd want is to do is show it the rolling road...

John :wink:
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PostPost by: Elanconvert » Fri Jan 01, 2016 5:05 pm

john........many years ago I had a midget with a slight knock on start up....in those days molyslip was a cure-all, which reduced the knock a bit........car ran fine for 10k miles, until I sold it.......
buyer later told me it was a camshaft bearing.......

:D fred :D
'Never give up!....unless it's hopeless.....'

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PostPost by: john.p.clegg » Fri Jan 01, 2016 5:23 pm

Sounds like a stethoscope may be a good idea?

John
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PostPost by: Mick6186 » Fri Jan 01, 2016 6:58 pm

I had an MG Midget with a knock/ rattle on startup for a couple of seconds before the oil pressure built up. It turned out to be a worn big end bearing and crank journal. A new set of big end shells cured it for a very short time, but a permanent cure was a crank re grind and new shells,
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PostPost by: mbell » Fri Jan 01, 2016 8:27 pm

I'd start with a wet compression test and see what the readings come back as. This should confirm if it's valve or piston ring.

As pointed out knock would be in the bottom end. Normally a worn bottom end is accompanied with reduced oil pressure. Have you seen much change in oil pressures?

Personally at this point I'd just monitor the knock and compression results. As to me (a non expert) it just sounds like a engine with some wear but not ready for a rebuild yet.

If you think it's down on power I'd be making sure the carbs are in good order and thinking about a tuning session for them.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: Type28 » Fri Jan 01, 2016 9:09 pm

Thanks for the response's.
The compression test was carried out with a hot engine and throttle wide open. I carried out the test dry and wet and there was no change in the compression readings. I had two compression testers to hand and used them both and there was very little difference in the reading. I suspect the previous machining work that was carried out to replace the valve seats was not that good? Does low compression have a noticeable effect on power delivery? If the valve timing was wrong would this have an effect on the compression?
I was going to remove the engine to have a look at the crank bearings, but had hoped to leave the top end alone, but after checking the compression I think it will be a strip down. I will check the timing etc and make sure everything is ok, if it's out I will adjust and retake readings.
I suspect the bottom end would last a while longer, but I would rather fix it in the winter months.

Thanks
George
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PostPost by: Type28 » Sun Jan 03, 2016 2:51 pm

hi Folks

I've decided to remove the engine and gear box over the next few days. Can anyone tell me the approximate weight of the engine and box- I have a few hoist options available.

Cheers
George
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PostPost by: Type28 » Sun Jan 03, 2016 4:43 pm

Found the answer to my own question , about 150 kg.
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PostPost by: billwill » Mon Jan 04, 2016 12:54 pm

I usually test the hoist first to see if it can lift the engine while still bolted in & see if I can raise the whole front of the car on its springs, but not usually as far as lifting the front wheels off the ground.

:D
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PostPost by: Type28 » Mon Jan 11, 2016 5:18 pm

I took the head of last week and will remove the rest of the engine and gearbox later this week.

I wonder if people with much more experience than me would care to comment on the inlet valve seating.
The valve isn't flush with the head when in its seat- could this be the reason for the low compression, or do they look how you would expect? New bronze valve guides have been fitted.

The engine has plus 30 pistons and they look brand new.
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PostPost by: rgh0 » Mon Jan 11, 2016 7:41 pm

They dont look abnormal in position. What vavle shim thicknesses did you have. That will normally tell you if the seats have been recut to many times and the valve recessed to far. However even if recessed to far this will have only a small effect on the compression ratio.

cheers
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PostPost by: Type28 » Sun Jan 17, 2016 9:18 pm

That's the engine and box out. I don't know enough about setting shims and valve clearances etc so I am Going to take my engine to AGRA engineering, they did my Cortina engine about 10 years ago and it's still going strong. I am going to get them to try and get some more BHP out the engine to make it feel a bit livelier.
Whilst the gearbox is out I wouldn't mind installing a close ratio gear box , the same as my Cortina as it's fun to drive :D , anyone got one for sale?

Cheers
George

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