Rats.. losing coolant.

[JJDraper]

A lovely day last week, all's well with the world. The car passed its MOT and I can look forward to another year of happy motoring. Started the car and noted a slight whiff of coolant as I moved off. This escalated to wisps of steam curling round the edges of the bonnet at a set of traffic lights, prompting looks of concern from other motorists. A quick look at the car park at work showed a dribble of water along the back edge of the cylinder head. No mayo in the oil, so no oil/water contamination. Time for a strip down. Monday was a good day, so I set to work in the workshop, and it was clear that the headgasket had extruded out slightly from the edge of the joint - see pic. A bit more work and the head came off exposing the cause of the water leak; a disintegrating head gasket. No sign of a cylinder/waterway breach, and no evidence of a crack (my initial worry after all the recent cold). As the head has done around 50k miles since its last teardown, I think a bit of maintenance is due.

A couple of queries to put to you all. Anyone else have this failure mode on a head gasket (rear water way to atmosphere)? Any thoughts on moving towards a really expensive gasket (Cometic, Cosworth etc) rather than the mildly expensive Ajusa that was in use. Thirdly, any thoughts on a service life for the head between rebuilds? Mine was fully refurbed (valves, guides, buckets, springs etc) about 6 years and 50k miles ago. The engine was running perfectly (still was apart from the water leak), so I had no thoughts of pulling it all apart for 'de-coke'.

I attach a few pictures of my progress so far for your amusement!

Jeremy

[billwill]

I'm not sure, but it would seem to indicate that you are getting excess pressure in the water chamber to force the gasket out at that point or your head bolts were not torqued up properly.

As far as I know the water pressure would only increase significantly if the water was above boiling point AND you have a radiator cap that is too high a pressure rating or has seized up.

[oldelanman]

From your photos the cutouts in the gasket look very large compared to the waterways in the head and block and the area that has failed is consequently very narrow. It's a very long time since my head was off so I don't know if that's typical or not but it could perhaps be the reason it failed.

[garyeanderson]

The folks that I knew back in the day when these were "current" autos used for everyday transportation used to say as a rule of thumb, 40k miles first valve job, at 80k miles a valve job and first bore to .010 or .015 inch, at 120k third valve job, etc. so I think you are due for some work, that said what was the "coolant"? There seems to be a fair amount of corrosion near the "break" in the gasket, if it were rusty, that could provide a path for the coolant to migrate outward. I have some NOS head gaskets to compare to yours I got the one on the right in 1993 when I bought an Elan and its gone unused. The on on the left has the 26E026 stamped in it so its not a 105E like the box says it is. My gut feel is that the rust on the face should be removed (decked) and head checked for flatness. its apart so a valve job too. I think you are in the deep end right now, better pictures of the block face would be nice and what the coolant was? 50/50 antifreeze or what? more questions than answers from me as usual.

[JJDraper]

Well, I have had my head examined and the head man agreed that the gasket failure mode was unusual.. He also thought that excessive pressure in the system may be a contributory factor, along with age & miles. The cap is a 10lbs unit, rather than the correct 7lbs one, but still seems a small change. Anyway I shall get a 7pounder and fit that. Head man says the head should be OK, subject to a full tear down. No signs of cracks or warping. Minimal skims during its life, so a light facing is all it should need. The pictures of the waterways look worse than they actually are. No real corrosion, but the gasket is mighty narrow at the back and the waterway hole in the gasket is much bigger than it needs to be. Surely there is not that much variation in waterway sizes? No real consensus on gaskets, although some raised eyebrows at the thought of fitting a Cometic unit at over 100GBP on a road unit. No sign of headbolt overtightening and as I put it on last time, I am glad of that..

The coolant is/was around a 35/65 mixture of a decent brand, but I can't be more specific as it was three years or so ago that it was last filled, with only a half pint or so top up since then. ( see elan-f15/cooling-system-robustness-improvements-t21159.html for last mention of cooling in the car).

As headology is out of my comfort zone, I will spend the time preparing the block for the refurbed head. Bores look fine, with no lip. New rings?? No oil loss or smoke, so I may leave well alone. I will add a few more pics as the job progresses.

Jeremy

[rgh0]

Overtime the differential expansion and contraction between the iron block and alloy head as it go through temperature cycles can give head gasket problems.

I suspect this has caused your gasket to fail at the narrow point betwwen the water passgae at the outer edge.

Ensure the surface finsh of the block and head is suitable for the type of gasket you use. The manufacturers quote a required finsh typically.

I have seen some racing heads fail in this location at high revs and load due to the head lifting slighty on the bolts and the gasket loosing compression - ARP head studs and a little more torque fixes the problem.


cheers
Rohan

[JJDraper]

... I think you are in the deep end right now,.

Bad news is that on full tear down, the Head man thinks the waterways at the back of the head need some 'light' weld to beef up the head face and then a very light facing to the head. Not horrendous cost, but I might have to extend the Lenten beer moratorium..

Good news is that valves, guides etc all in A1 condition after a clean up. Also, included in the cost is machining the breather hole to the right diameter, as it had never been machined correctly - see picture - anyone had this before? The pic is from the last head rebuild which was 8 years ago ( a bit of corrosion even then)..

Still, cheaper than a new head (although Mrs D thinks I need one).

Jeremy
PS just idly playing with a calculator - 60,000 miles = 200million engine revs (give or take a few) = 50million actuations for each valve!

[JJDraper]

Head is back on and engine now running smoothly. No sign of any leaks so far. This is the third head gasket replacement in my ownership and it seems to get easier once you get going. Cold weather and rain delayed the event, but all done now. The head came back all set up and ready to go. I can just about cope with cleaning stuff and putting the bits back together. The pistons came up a treat with a light scrape with a blunt edge and finish with acetone and a nylon scourer. The block is as clean as I could get it - a bit of corrosion, but hopefully it will hold. No worse than last time. See pics for my home brewed technique, learned from de-coking old motorcycles. The grease around the piston/cyclinder gap is amazingly effective, and the acetone is excellent at dissolving caked on deposits. Don't use vinyl gloves with acetone! Latex gloves are fine and don't go all gooey.

I used Wellseal on the cork watercover gasket and nothing on the Ajusa head gasket. Once I got going, the head was back on & torqued down in an hour or so, with the cam chain and valve timing surprisingly easy this time. The most difficult bit is seeing the timing marks on the sprockets with the bonnet (hood) in place. The side view always seems to suggest the marks are way out, but a straight edge on the water cover showed they were as close as they can be without offset dowels. I noticed that the sprockets looked a little pitted on the chain drive faces - next time. The sprockets didn't look particularly worn or hooked and I believe it had a new chain when the current pistons were fitted (about 90k miles ago), but there is plenty of adjustment left. The bores still look pretty good with no discernible wear lip, just a light polish where the rings are under pressure.

The next stage; fitting all the ancillaries and timing the distributor seem to take forever when all you want to do is start her up! The time came and I turned the key - it tried, but the battery was a little too weak. An auxiliary battery connected, it churned over, and coughed into life. Hooray! Clouds of smoke and steam provided some entertainment for passers by, but this is normal and the engine settled into a nice steady beat.

Went out for a 60 mile shakedown run this morning and all is fine, engine feels strong, with a bit more urge than before, when I ventured past 4,000rpm. Seems sharper, but that may be all in my head (!!).

Happiness is back.

Jeremy

[Henry VIIII]

It's always nice to see nice shiny piston tops, but they used to say in the old days that you should leave a thin layer of black.

I never found out whether or not that actually made any difference.

[JJDraper]

Yes, the manual actually mentions that, something about reducing the bedding in time for the combustion chamber. Can't say I have ever noticed any effect one way or the other with any of my motorcycles and other cars. Makes me feel better seeing the pistons shiny!

Anyone out there got some actual data on the practice? This may come from the days when you did a de-coke every few thousand miles.

Jeremy

[512BB]

What do you mean 'when you ventured past 4000 rpm' Jeremy. You have only just torqued the head down for the first time!

I would let her bed in for 500 miles or so, not reving above 3000, then re torque the head down, before venturing past 3000, let alone 4000. Unless of course you fancy practicing head removal again.

Leslie

[JJDraper]

I haven't driven a Lotus for a month - couldn't help it!!!!

Jeremy