Engine problem...must be head gasket?

[type26owner]

Martin,
I followed some recent advice that was well intended but wrong I'm afraid. The high capacity, high pressure oil pump does it's job great. Just that the range of pressure is too high. I'll try the 0-20W Redline to see if that cures this problem and if it doesn't I'll install the regular oil pump.

The reason there is a big difference between dino and synthetic oil is the film-strength. The synthetic is six times higher.

My buddy who is a Phd lubrication expert swears by the synthetic. He and I developed a CVD low temperature process to coat toolbits with titanium nitride hard coating in about '82. It was his graduate thesis. We broke new ground there! Science is fun sometimes.

[denicholls2]

Don't run the engine any more or you greatly increase the probability of warpage or other significant damage blowing things around where they don't belong. Significant water in a cylinder is non-compressible and may cost you a piston, rod, or both. You know you need to replace at least the gasket; so pull the head pronto and find out what else is wrong in the top end. Having the head off certainly won't make it any harder to pull the engine later if needs be.

Once the head is off you have good access to everything but the bottom end, and everything related to your current problem (though a botched rebuild likely has worse bottom than top-end issues waiting to bite you in time.)

Valves are inspectable with the head off, as are the bores. Any scoring and you've got a ring problem (unlikely based on your description). An engine this close to new should still show clear hone marks. If it's glazed over and has any ridge at the top of the bore, your PO is a liar, see below. Otherwise, you got lucky. If all the bores look OK and similar, you skated and can just hope for the best on the bottom end. In that case you're no worse off than if the gasket hadn't blown, so...

Was the head retorqued after running-in? If not, that may be the whole of your problem. You can confirm this first only before doing anything else by retorquing it (for this test don't bother to back off first as you would in doing it properly on a good healthy engine). If you wind up tightening anything more than a tiny bit, you have your answer -- bolts were loose due either to neglect or overheating, and the gasket had little choice but to let go. Unfortunately, knowing this step was skipped still won't help you now.

If the water pump looks new, leave it, it was probably done with the rebuild (and you have more happy evidence there really was a rebuild). Unless, of course, you want to spring for a cassette. If the pump isn't new, then you can be pretty sure the "rebuild" involved fixing the just the broken part and putting the rest of the engine back together on the cheap (possibly even with the old gasket) and that you have more money to spend either now or down the road. Especially true if the bores didn't indicate recent machining.

If the head was touched by a machinist within the last 3,000 miles, there should be plenty of visual cues on top and bottom sides that this is the case. If it's flat and shimmed to spec, put on a smile and leave it be. If the head's warped, you know for sure why the gasket failed, and probably that you don't really have a rebuilt engine.

If you have the coin and know the engine really wasn't REALLY rebuilt (from above), then it isn't that much more work to pull it and make sure of things like bearings large and small, chain, clutch plate, throwout bearing, and thrust washer. I'd do it just for peace of mind while my hands were greasy as the DIY cost is not great and most of the cost of a TwinCam rebuild seems to be in head work. If it's really a recent rebuild, there won't be any machine work to do, which is where the real cost lies. Bearings, rings, chain, gaskets and seals (maybe an oil pump) won't add up to all that much, though they'll be a lot more than just leaving it be.

But if you know you'd be prone to shipwright's disease (blueprinting, line boring, etc) that runs into serious change, then let the sleeping dog lie for now. Slap on a gasket, drive away cheap, and pray for the best.
Best of luck in any course!

Doug Nicholls, 54/1822 Ma~

[rgh0]

Keith

In normal road use a high volume, high pressure pump will produce the results you have unless the engine has excessive bearing clearances, which yours clearly does not have.

I use Redline 20-W50 with a HV/HP pump. In normal road use it sits on the pressure relief valve pressure at 60 PSI. On the track it sits at around 40 to 50 psi once the engine is fully hot and running between 5000 and 8000 rpm. It idles hot about 25 to 30 psi with road use and around 15 to 20 psi at the end of a race. I run a small oil cooler in front of the radiator also.

You have a challenge matching the range of your uses to the oil capability. The 60 psi and continuous relief valve flow should not do any damage in road use. Too low a flow and supply pressure on the race track has more chance of being harmful. I would stick with the HP/HV pump given your track use and try to find the right oil grade to match both road and track use for your particular engine build. I build my engines with main and big end clearances at the top end of the Lotus specification range to maximise oil flow and bearing cooling andm inimise risk of a bearing siezing if it goes wrong ( been there done that).

Rohan

[type26owner]

Rohan,

It's always a challenge to Lotus at the hairy edge. BTW, did the bigend bearing sieze on your avatar?

I'm not going to do anything until I install the oil heat exchanger (warmer) in the top tank of my Marsden radiator. Suppose I'll just bite the bullet and have another exact copy of Marsden made up brand new again but with the heat exchanger included this time. That way I don't have to sideline my car for a whole week. Wish I'd thought of that feature when I had the last radiator built two years ago.

There's a good chance if the oil temperature would just stabilize at around 100C the 10-30W Redline will provide the oil pressure a lot closer to the ideal.

[berni29]

Hi All

Well, I took the head off. Once the bolts were undone oil started to seep out of the sides, then the lightest of taps with a rubber hammer and it virtually slid of the block by itself. I will post picturres later today for expert comment, but a brief description of what I found.....The block looks ok, the waterways are a bit corroded and the small holes in the gasket were blocked. The block face still has the "made in england" and some numbers lightly stamped into it, so I guess that it has not been skimmed. The pistons have some carbon deposits on, and the bores are very glassy with no discernible step in them as felt with a finger. There are a couple of light scratches in the bores. Having said this, I have not had a look at No1 & 4 yet because the engine is at TDC. The gasket is very much in one piece, but is discoloured particularly between the bore holes. The head, well, it is heavily (in my opinion) carboned up and will be coming apart for a big clean. If the car has done 81,000 miles (and the history bears this out) then I would say that I am looking at 81,000 miles worth of carbon, but I am no expert. The surround (7mm wide or so) to one of the triangularish waterways almost looks lumpy, like it has rust bubbling up around it. I do not like the look of that! Apart from this I have not had the time to inspect the head.

I will post pictures ASAP. So much for the PO's rebuild!!

Berni

[rgh0]

Keith

The rod in my avatar failed when a con rod bolt broke due to a fatigue crack at the thread root. The engine was in its second race and had only about 10 hours on it from a total new build including new carrillo rods and rod bolts.

I put it down to incorrect assembly by me (most likely) or perhaps a faulty bolt that had a crack in it from new( less likely). Since then I have always used a stretch guage on rod bolts to ensure correct tension rather than just rely on torque specifications.

Made a total mess of the engine. Smashed the block, sump, deeply scored and ruined a steel crank, smashed the cams and jack shaft, chewed up the oil pump, bent all the valves, put dings is all the other rods and pistons etc etc. The only thing I recovered from that engine was the head and front cover and flywheel.

The seized big end I had was much less dramatic. It only required one new carrillo rod and a bearing as the old rod had been heat affected and lost its heat treatment and gone soft. The crank just needed polishing and slight straightening, those Datsun cranks are made of tough stuff. Spent a lot more time on sump baffling after that incident as it was due to oil pressure loss on a long right hander. I had gone though that corner for years without a problem but modifications to suspension had me going faster than normal and this pushed me over the edge.

you live and learn !

Rohan

[Dave-M]

Rohan, Would you please educate me regarding the Datsun crank you mentioned in your last post.
I have an 1500 pre crossflow engine to build. You probably know that this engine block was the basis for the twin cam. I am hoping for around 130bhp and a tougher crank can only be good.
Regards
Dave-M

[rgh0]

Dave

The crank is out of a Datsun 1600 / Bluebird ( L16 crank is its designation) can be machined to drop straight into a ford 1500 block. The crank is forged steel and good for 9000 plus rpm and gives a great racing crank at about one third the price. The crank from the Datsun 1800 engine (designation L18) as used in the 180B here in Australia can similarly be fitted into the 1600 block for a long stroke engine. This crank is even better as its a 8 counterwieght crank compared to the 4 counterweight design of the L16. I have never seen one of these cranks break, Datsun sure overengineered them for the 1600 engine, something else in the engine always goes first. Just about everyone raing twincams or ford 1500's in Australia uses this crank. You go to a Dtasun wrecker to find one and they ask " Oh you race a Lotus do you !". The second hand crank price used to be around A$50 it now gone up to around $250 in response to demand from the racers.

The only detail issues with the mod are

1. A couple of non structural lugs in the bottom corners of the Ford block need to be ground off a little to clear the larger counterweights.

2. You need an oversize thrust bearing on one side as the spacing on the thrust faces on the crank is about .010 inch wider.

3. For a standard stroke on a twin cam you end up with the journals .010 undersize compared to standard twin cam.

4. The crank has 5 metric bolt holes in its back end so you need a new flywheel. If building a high revving engine a new steel or aluminium flywheel is a good idea anyhow.

The Elan Factory among others in Australia does this mod and their web site has an information sheet on the crank and the various options in terms of heat treatment etc . It is not complex machining to make it. There was a web site in NZ with photos and more specific instructions from a guy who had done it their, dont know the URL but a bit of searching should find it. If you have a Datsun crank and a Ford one to compare it to, any competent crank rebuilder should be able to machine it up and get it balanced.

I have some photos of the last build I did using a Datsun crank so I can post them if you wish.

regards
Rohan

[Dave-M]

Thanks Rohan, Great info. Can you post the pictures please.
In light of what you say I may do a tall block pre crossflow with steel rods,
assuming I can find a crank here in the UK.
Most of the old style scrap yards here in the UK have closed due to government legislation and the remaining ones are catering for modern cars and are very expensive, but the search is now on.
I'll let you know what happens.
Regards
Dave-M

[type26owner]

Dave,
You might consider just buying a new steel crankshaft. I had to replace the one in my BRM a couple of years ago and it was $1700. That seems like a lot but we bought one back 1970 and it was $1700 back then also. It's a downright bargain nowadays.

They are also frequently offered used on http://www.race-cars.com/.

I must admit I'm too cheap to buy one for my Elan. The harmonic balancer is all it gets to prevent a broken crankshaft from me flogging it really hard.

[Dag-Henning]

- just got a new four bolt EN 19 steel crank ( FIA-legal) from QED. Think it was ? 950......Not cheap, but safe....( against both revs and inspectors.... )

Dag

[rgh0]

Dave

I have posted some photos of the Datsun crank going into the block on the Yahoo group - elanmods photos section

Here is the URL for the Elan Factory datasheet on their Datsun crank conversion

www.elanfactory.com.au/pdf/product_data ... ersion.pdf


Rohan

[Dave-M]

Kieth,Dag & Bernie,
Bernie,
Sorry, Without realising it I hi-jacked your thread will not do it again, promise. Your head gasket problem looks like a straight replacement will fix it. I have seen a few like this before. I would just clean it up and fit a new gasket. You dont use full RPM all the time do you?
Kieth & Dag,
I have too many cars in my collection to throw ?1000 at a crank. Being a Yorkshireman (Read,- scrooge, tightwad or any other colloquial expression) I prefer to maintain the value of my cars by not throwing cash at them but enterprise and effort. The datsun crank is an ideal example of value for effort not money.some of the other opportunities to improve my cars are ebay trading to upgrade parts and using my skills instead of paying others.
Rohan, Superb information, Thank-you. If you will excuse my ignorance of Japanese cars, Can you tell me the years the Datsuns in question were produced?
Regards
Dave

[M100]

Dave,

a few years ago this Datsun alternative crank was mentioned on one of the Elan mailing lists and I went off round a few scrapyards in a search for a suitable donor car without any luck. If I recall correctly the crank was used on a Datsun Violet and Bluebird (70's - very early 80's vintage) and while the mechanicals on these go on forever the bodywork will have consigned the cars to the scrapyard many years ago (you forget Rohan lives where cars don't rust!)

Good luck and if you find more than one can I have first shout on the other?

[rgh0]

Dave

I dont know what Datsun cars the engines were sold in in the UK but Matins timings sound about right.

In Australia the 1600 engines were in the Datsun 1600 sedan ( Bluebird in the US and UK ? ) sold in the late sixties and early seventies. The 1800 engine was sold in the Datsun 180B sedan sold in mid to late seventies.

These cars were made in Australia and sold in fairly large numbers and with our long car life due to no rust problems there are still a reasonable supply of engines in the wrecking yards though it is getting harder to find the 1600 cranks which is why I have 2 spares, which should last out my racing career

Rohan