Lotus Elan

Oil leak, front of engine

PostPost by: 2cams70 » Sat Feb 01, 2020 10:06 pm

The Veg wrote:More bad news. I just checked this bolt and thought it seemed loose. With very little torque applied -not even beginning to feel tight- the thread in the head stripped!


Look at it this way - at least you know a few more things this time before you pull it down so hopefully you won't have any issues this time round. When you get in there - and I would suggest replacing the sump gasket too - with cork gaskets go around all the bolts and only torque them up ONCE. If you keep go over the bolts and rechecking the torque even after they come up to torque once the gasket will still keep compressing, become overstressed and start to extrude. Use a torque wrench and tap the sump flange flat around the bolt holes too if around there it has become distorted over time.
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PostPost by: The Veg » Fri Feb 07, 2020 11:21 pm

UPDATE:

I've got the head off and have had a look at that downward-facing hole and it doesn't appear to be as bad as I thought. Turns out that the bolt that was in it wasn't very long and only engaged a couple of threads- so it stripped maybe two outer threads at most. If I clean them up with at tap and use a bolt half an inch longer (the hole is deep enough) it should be fine. In any case, the hole doesn't go through into the timing compartment so this probably wasn't a major leak-point. The search for the spraying leak continues.

In the process of opening the head I decided to check the valve clearances and I'm glad I did- 7 of 8 were out of tolerance! Since this engine was rebuilt not that many miles ago (don't know how many but the freshness shows), I'm not sure why- but I'll get that corrected before it goes back together.

And of course I'll start reading all the threads here about gaskets and goops and such, and with any luck I can make it reasonably oil-tight for a while.
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PostPost by: StressCraxx » Sat Feb 08, 2020 2:15 am

One place that's easy to spray oil vapor is the dipstick tube. I put oil resistant RTV between the split halves and a spark plug boot over the sealed area to seal the dipstick. That helped a bunch.

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PostPost by: The Veg » Sat Feb 08, 2020 3:07 pm

At the moment I don't have a spare boot, but plan to implement this suggestion as soon as I do have one.
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PostPost by: benymazz » Sun Feb 09, 2020 6:47 am

The Veg wrote:In the process of opening the head I decided to check the valve clearances and I'm glad I did- 7 of 8 were out of tolerance! Since this engine was rebuilt not that many miles ago (don't know how many but the freshness shows), I'm not sure why- but I'll get that corrected before it goes back together.


In my experience, valve clearances generally tighten up a little bit when you torque the cylinder head down. Usually about 1 thou, sometimes 2. Not all cylinders are affected evenly - for instance, when I torqued my head down a couple of weeks ago, I-2 tightened up from .008 to .006 but I-4 stayed at .008.

Fortunately, whether by dumb luck or skill, after 800mi of running in all of my clearances are still in spec so it looks like I won't have to pull the cams and re-shim anytime soon (whew).

StressCraxx wrote:One place that's easy to spray oil vapor is the dipstick tube. I put oil resistant RTV between the split halves and a spark plug boot over the sealed area to seal the dipstick. That helped a bunch.

Regards,
Dan Wise


Dan, could you post or send me a picture of this? I thought I saw somewhere that from the factory there was some sort of grommet that fit around the dipstick tube. If there was, mine is long since gone, and I had been mulling ideas for how to stop oil droplets from flying out of the dipstick tube and invariably coating the surrounding area in a nice glaze of oil (for what it's worth, this appears to only be a problem if I go on a spirited drive and get the RPMs above 5,500... maybe I need to go slower...)

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PostPost by: oldelanman » Sun Feb 09, 2020 8:21 am

Heat shrink sleeve is another way to seal the dip stick and stop it rattling around. Not as pretty as a spark plug boot perhaps but just as effective.
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PostPost by: richardcox_lotus » Sun Feb 09, 2020 10:36 am

That would probably work better. I tried the spark plug boot method and it forced the dipstick handle end to touch and rattle against the dynamo pulley.

Oh well. If anyone can take a decent picture of the spark plug boot solution, in situ, that would help.

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PostPost by: alan.barker » Sun Feb 09, 2020 1:36 pm

Try putting a light spring between the dipstick handle and the generator bracket :wink: :wink:
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PostPost by: prezoom » Sun Feb 09, 2020 6:06 pm

I added a throttle return style spring about 10 years ago that hooks through the dip stick handle. Bent a finger loop above the hook of the spring to easily lift the spring off the dip stick handle, similar to the ring on the end of the bonnet hold down springs. Along with a thin AN washer slipped on to the dip stick, which bumps against the hump, and a small O ring below the washer. The spring pulls the O ring tight against the tube to enhance the seal. A small hole was drilled in the alternator adjustment bracket to locate one end of the spring. Yes, it does move the full mark a slight bit upward, but I can deal with move as it is a very small amount. Did not bother to create a new mark, knowing where the oil level is now shown on the stick. I suppose I could have knocked the tube down a bit to align the oil to the full mark. It has stopped oil vapour from the crank case from being pushed out from pumping pressures in the block.
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PostPost by: The Veg » Fri Feb 14, 2020 2:51 am

benymazz wrote:
The Veg wrote:In the process of opening the head I decided to check the valve clearances and I'm glad I did- 7 of 8 were out of tolerance! Since this engine was rebuilt not that many miles ago (don't know how many but the freshness shows), I'm not sure why- but I'll get that corrected before it goes back together.


In my experience, valve clearances generally tighten up a little bit when you torque the cylinder head down. Usually about 1 thou, sometimes 2. Not all cylinders are affected evenly - for instance, when I torqued my head down a couple of weeks ago, I-2 tightened up from .008 to .006 but I-4 stayed at .008.

Fortunately, whether by dumb luck or skill, after 800mi of running in all of my clearances are still in spec so it looks like I won't have to pull the cams and re-shim anytime soon (whew).


That tightening after torque is a new one on me (why does that happen?), but then this is my first Twin Cam and of the few other shim-type engines I've had before, I've never done the clearances with a head off. 'Half an exception' to that with my former Esprit, in which the cam-housings had to come off the head to get to the shims and the liquid sealant used under them must be taken into account when deciding what shim thicknesses to use.

Anyway, I measured the clearances with the head still under torque and all four intakes measured .004, exhausts at .008, .011, .014, and .016.

I don't know if it matters, but the PO who had the rebuild done had the head done to DBE Stage II specification with the DBE 112 cams.

I forgot to order the new shims this week but there's no real hurry, especially since I still don't know what else I'll discover that will need to be added to the shopping-list.
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PostPost by: rgh0 » Fri Feb 14, 2020 9:58 pm

The Veg wrote:.....That tightening after torque is a new one on me (why does that happen?),.....


I have observed the same slight closing up of valve clearances on some cylinders when the head is bolted down. Generally less than 1 thou. I believe its due to the head itself compressing under the head bolt loads thus making it fractionally shorter and the valve sticking up fractionally higher as a result. I generally set the valve clearances at the top end of the specified range and find some may shift to the middle of the range as a result.

if the cams or cam tunnels are not straight or the head slightly warped you can also get some larger shifts in clearances when bolting down the head

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PostPost by: The Veg » Sat Feb 15, 2020 1:13 am

So if the head was under torque when I took the measurements, should I disregard trying to account for this when choosing the new shims?
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PostPost by: rgh0 » Sat Feb 15, 2020 3:28 am

Yes if you measured the clearances with the head bolted down and are resetting the shims based on those measurements then you should be able to ignore any shift that may occur when bolting down the head

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PostPost by: The Veg » Sun Mar 22, 2020 2:09 am

Small update and 'sanity-check,' if you will:

I'm getting ready to put everything back together (head, sump, front cover, etc.) and was reading the WSM to make sure I understand everything, starting with the sections on dis-assembly. It mentions removing the oil slinger... ¿Huh? That didn't sound familiar, and after consulting the parts manual, I definitely did not recognize such an item when I was taking it all apart. Read some old threads here to familiarise myself with it and what it does, and the upshot is that the person who did the rebuild forgot the oil slinger.

I don't think the slinger's omission was a big factor in my leaks, since I couldn't find any evidence that the front seal was the source, but it still bugs me.
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PostPost by: alan.barker » Sun Mar 22, 2020 7:10 am

Well that's a bummer to say the least no Oil Slinger. For sure you need to fit one.
I hope the Post is still operating where you live and not like here in France on shut down :shock:
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