Lotus Elan

Dipstick Blues

PostPost by: type26owner » Sun Apr 10, 2005 9:25 pm

Wow! The fluorescent dye clearly shows the source of my oil leak. It took maybe two minutes of running time for it to start to weep the dye stained oil out. It was from the timing chain cover backplate to engine block where it was leaking on the dipstick side. Guessing the leak rate was about one drop every 60 seconds at most.

When I sealed that cover when the engine was assembled I just used a silicone adhesive. Clearly that's not enough to ensure there's not an oil leak from there. Wonder if adding a thread of surgical suture would help block the flow synthetic oil? For now I'm coating the leaking seam with the 3M exterior sealing junk I bought. Looks to be a lacquer based clear semi-hard gel coating. If this stuff works I've got the engine completely oil tight I think. Going to clean it carefully and watch it for the next weeks for anymore piddling.

p.s. Rohan, the Redline oil is slightly fluorescent as a greenish tint without adding any dye. The dye shines as a bright orange color.
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PostPost by: type26owner » Mon Apr 11, 2005 2:58 am

Have fixed the leak around the dipstick area okay. Found a new one from the backside of the head. Seems the oil has been seeping under the head of the lefthand rear headbolt and is weeping out from the headgasket. Have to figure out how-to seal around all the headbolt's heads and washers to stem the flow of oil down the bolt from now on. Applied the 3M sealer in that local area and it looks to have stopped that leak too. Never expected to have an oil leak from there. The dye is very revealing and I'm completely sold as to it's value. I never could have been able to have stopped up all the leaks without it. Along with the blacklight and dye you need a pair of the yellow safety goggles which just about doubles the fluorescense and makes the stuff appear to glow brightly. It can't be used direct sunlight though. It doesn't have to be completely dark either, the light coming in from an overhead skylight was no problem.

The Payen JM460 camcover gasket is the next problem it appears. Got a glow from it all the way around the gasket. Is there a different brand of camcover gasket available anywhere? Perhaps it can be sealed with some sort of thin penetrating sealer so it won't bleed through synthetic oil from everywhere.

For the very first time I didn't have a single drop fall on my driveway when I got home. :D
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PostPost by: rgh0 » Mon Apr 11, 2005 9:36 am

Keith

For the back plate to block join I always use the original paper gasket and Loctite aviation gasket cement. You could probably use some of the loctite anerobic gasket sealants to replace the paper gasket if you wanted to as an altenative. In general silicone sealants dont work well with close tolerance metal to metal joints in my experience such as the back plate to block join as they tend to squeeze out leaving a dry join unless you go through a careful 2 stage assembly process to form the gasket and allow it to set before fully tensioning the join.

The leak out the cam cover gasket though the cork I have also observed. I see the same around the sump gasket also. I just keep regularly snugging the bolts down as the cork compresses and creeps to minimise the leakage and I have found that I can keep it to just slightly oily cork that I need to wipe over after a weekends racing or a few months driving on the road. The alternative is to redesign these joints to take an o-ring or some other system.

If youve got to the no drips on the drive then your ahead of 99.9% of Lotus owners so congratulate yourself !

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PostPost by: M100 » Mon Apr 11, 2005 12:04 pm

Why all the troubles with getting a twin cam oil tight?

My 72 Sprint engine was rebuilt about 15 years ago, does around 3000 summer miles a year and (touch wood) there is no oil seepage anywhere. Before some wag asks the obvious, yes, the sump is filled to the correct level. (with Mobil 1)

Although not bad enough to drop leaks onto the floor, as of today I have bigger leaks on my 90's Elan sump/turbo drain hose.
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PostPost by: tdafforn » Mon Apr 11, 2005 12:41 pm

If you're using a bulb which emits at <280 nm be a little careful as a they can pose significant risk of sun burn and skin cancer.
We use them all the time at work (visualising DNA) and always wear full skin coverage (Gloves, special full face visor and lab coat). Had a number of duff visors once and a load of guys in the lab ended up in hospital with burnt corneas.
take care
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PostPost by: type26owner » Mon Apr 11, 2005 2:11 pm

Hi Rohan,
Thanks for the compliment. You're absolutely right about there not being enough space for the silicone adhesive to perform well with a zero clearance fit and the amount of motion caused by the CTE. Perhaps a shallow groove about 3mm wide would do the trick and allow the silicone adhesive to do it's sealing thing. What about a way to seal the top of the headbolts? They must be oily while being torqued up. Have you any suggestions on how-to seal up those puppies reliably? The use of silicone adhesive on the headgasket is not up to the task to blocking the oil from oozing out from there again from the huge CTE that gasket endures.

Hi M100,
I think you probably have a later 6-bolt crankshaft twinkcam with a rear lipseal. Those are considerably easier to get it oil tight though most aren't. You should be feel privileged to own one of the very few engines which does not spew out oil.

Hi Tim,
Thanks for the heads up. I'm fully aware of the dangers of this type of radiation. My full time job is designing x-ray optical devices for the Advanced Light Source. The spectrum ranges from the infared to the hard x-rays.
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PostPost by: rgh0 » Tue Apr 12, 2005 9:49 am

Keith

I dont have problems with oil leaks around the head bolts and head gasket. I use a locally made Australian gasket based on the gasket technology that is used in current Fords made in Australia that use a similar alloy head and cast iron block to the Lotus, as I understand it. They are made by a local one man company who will make any head gasket you want to any thickness in the range between about 1.3 and 2.5 mm uncompressed, provided you have a template for him.

The basic gasket design is a 3 layer design with 2 outside layers of synthetic fibre material and an inner perforated metal sheet layer. The outer layers are slightly dimpled and covered with something that looks like silver paint ( but is I am sure is more high tech). The bolt holes and water passages are stamped though the gasket. The oil feed to the head and the combustion chambers are sealed with a metal C ring formed around the gasket.

The gaskets is designed to be fitted without any sealants and I have never had any problems with them even in 13 to 1 high compression racing engines. I also ensure my head and blocks are flat and with the right surface finish which I am sure helps also.

I can take and send / post some photos if your interested in seeing the design differences compared some of the other commonly available gaskets

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PostPost by: type26owner » Tue Apr 12, 2005 2:13 pm

Rohan,
I'm using a modern day fiber type headgasket too. Mine is made by Fel-Pro. Most all the racers use this one because they don't easily spring a leak between the cylinders. An e-mail address for your gasket guy would be appreciated.

The headbolt which leaks is the one that has bulge out in the rear of the camcover to clear it. Like I stated before I never would have found that leak without the dye. Betcha lots of folks have an oil leak there and have just assumed it was coming from the rubber half moon above. Luckily on the 120 Ford block there is a protruding lug there which sticks proud of the head and the oil pools there before streaming on down through the bellhousing and dripping off the bottom. The thing which gets to me is it only took 15 minutes of the engine idling for the dye stained oil to drip onto the floor from that headbolt leak. Damn it, that synthetic oil is extremely mobile I presume due to it's unique surface tension properties. First thing that comes to mind is I might have a localized overheating issue around that headbolt and as a result the CTE is overcrushing the headgasket there. However the waterpassage in the gasket is within about 6mm of the headbolt hole also so one would expect a water leak there too. The cooling system is leak tight though. I'll have to call Loctite and get a recommendation on how to seal around the head of the headbolt. Always figured the oil oozing out of the side of the headgasket on the intake side was from the drain holes for the old pushrods. Now I bet it's also coming from those headbolts too. Didn't think to shine my UV lamp down under the carbies to look for any orange glowing sign of trouble.

When my son first pointed the drip out I momentarily panicked thinking it was from my newly installed rear main lipseal. My panic turned to instant joy to see the oil leak source was not actually from my lipseal modification on the 4-bolt crankshaft afterall. My key to happy Lotus ownership is to embrace and relish the challenge of fixing a really bizarre leak like this one. :D
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PostPost by: type26owner » Mon Apr 18, 2005 1:42 pm

Found another pinhole sized oil leak with the dye. Didn't need the UV light to spot it this time. There is a trail of oil that left a dark brown stripe on the Ford Light Blue paint of the engine. Have to try removing it with the special cleaner and hopefully find it does not permanently stain the paint. If it does it's a small price to pay for the huge benefit of making the leaks very easy to find.
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PostPost by: mikefromengland » Tue Apr 19, 2005 10:41 pm

all these leaks .my car is a 1971 +2 .it leaks alittle oil so what it lubricates the chassis a bit.what do you expect for a 34 year old car.mine might leak oil but its very reliable.thats probably why the original waranty only cost 8 pounds.just drive it have lots of fun and not lots of trouble usualy serious .ps who came up with that quote.kind regards mike :D
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PostPost by: type26owner » Wed Apr 20, 2005 1:18 am

Hi Mike,
Yeah but.... I'm taking it out on the race track. Oiling down the track is not very good manners. Also the track people really get upset when you creat a pool of oil in the paddock. It tends to dissolve the pavement.

Have already gotten the meatball flag and was ordered off the track when my wife foolishly lent me her C5 Corvette and I blew out the rear transmission seal. It's rather embarrassing and I intend for that never to happen again with any car that I'm driving. I only got a few laps in and it spoiled the day.
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PostPost by: rgh0 » Wed Apr 20, 2005 11:15 am

Keith

I have only ever got the meatball flag once in my Elan. I had assembled the motor and run it in and it was first time on the track for the new motor. Started blowing big clouds of smoke in the first corner immediately.

I discovered I had not got the real semi circular seal between the sump and block in place properly and the oil sloshing around in corners at racing speeds was coming out and onto the exhaust. I spent the Saturday night in the paddock on my back in the mud refitting the sump so I could race on the Sunday

I now take extra care assembling the sump and dont put the flywheel on until the sump is in place so I can check that gasket is properly located!

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PostPost by: M100 » Wed Apr 20, 2005 11:43 am

<!--QuoteBegin-type26owner+Apr 12 2005, 02:13 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (type26owner @ Apr 12 2005, 02:13 PM)</td></tr><tr><td id='QUOTE'><!--QuoteEBegin--> The headbolt which leaks is the one that has bulge out in the rear of the camcover to clear it. [/quote]
If the head top face is truly flat and so are the washers and the back face of the head bolt then you've got to be really unlucky to get an oil leak from there.

Maybe spot facing the head / lapping the washer / truing up the back face of the head bolt would fix it without using any sealant. Changing to arp head studs and nuts would give a proper solution - bolts are never a good idea for head to block clamping.
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PostPost by: type26owner » Wed Apr 20, 2005 2:03 pm

Rohan,
We all mess up every once in awhile. My brother and I left the chain tensioner loose last year and it fell out while he was on the track. Ran just fine until the ignition was switched off and then the pistons caught up with the all the valves. It was ugly. :(

M100,
Just one tiny problem with that plan. The head must be rotated to allow the rubbing pad for the timing chain to stick up into the well. Makes the alignment process using the dowel pins a real pain in the butt. With studs it would be even more difficult cause they would have to be threaded into the block after the head is positioned onto the headgasket. Not aware there is a benefit with using studs. Could you explain how that works please?

The aluminum under the washers has been plastically deformed into a bellmouthed shape and is chewed up. Have had to ream the clearance holes out several times already so the ARP bolts would pass through without binding. An insert is probably the way to go to slow down the yielding of the aluminum head. Haven't stared at a head to see if it's possible or not though. A sealant is the simplist solution. I'd be surprised if Loctite didn't already have the right product.
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PostPost by: rgh0 » Thu Apr 21, 2005 12:20 pm

Keith

Inserts under the head bolts can be done and I have seen done to recover heads that are soft and suffering from head bolts sinking into the aluminium and loosing tension over time leading to head gasket failures.

The machining and pressing in of the inserts can distort the head around the bearing caps and it may need line boring of the cam tunnels after.


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