Morgan +8 Forum

The cap I am using now is one of my old 7 psi caps that I had drilled for venting. It fits tightly, but does not have any pressure capture ability. it breaths through the recovery tank overflow.
'Works quite well. I installed this modified cap last year as I was too lazy that day (I really wanted to drive) to go to the NAPA store and get the PN that Fred listed.

I often make small changes to see what happens once I have a system sorted out.

As for the BLOCK/COMBUSTION GAS CHECK, I have found that in some cases (my Ford 5.0 V8 race road/race engine in particular, with alloy heads, and an I-6 Mercedes), a blown head gasket escaped detection for a couple of months until I let the engine get up to running temp, where it began to show the presence of a gasket leak. I was somewhat happy with this result (but not having to take my street/daily driver/racer apart during the week for a repair. Also happy that it was not a block failure, as the 5.0 block can sometimes split in half down the center, but that's another story). The real clue prior to this higher temperature check was an overheating indication on my temp gauge on the way to work (a 10 minute drive in traffic), but with a cold radiator. No coolant, with a loss over a couple of weeks of daily to-and-from. Previous to that, I had a very unusual overheating problem at the track, but no problems on the way to the track (a 100 mile, 80 mph dawn patrol drive) or on the return trip (not quite as fast, with some stop-go in traffic, A/C on, 95F ambient. Water loss was not significant (perhaps single digit ounces) as the coolant recovery bottle was at an approved level, much as I had filled it prior to my return from the track. Note that even on the injected Ford V8, a cylinder balance check didn't show a significant RPM change when the injector to that cylinder was cut. The test at a higher running temp finally detected the leak.

The plug in the bad cylinder didn't show anything untoward, but when the head was removed, the piston was beautifully cleaned. By that time, the leak had become more detectable, but the initial discovery required a longer test with the block test and indicator fluid. The failure was at a small water gallery near the combustion chamber fire ring. I could see how this might not be detectable until the engine got up to temperature.
I took the opportunity to true both heads and replace the gaskets. I didn't have any problems after that, nor did the next owner. The engine ran over 8000 track miles during its 120K tour with me.

The thing here is to perhaps test longer even if you don't get an immediate result with the fluid block tester.
I have used this longer test period to detect other head gasket leaks on other cars, and found after tear down, a head gasket failure not previously detected, even though the car had suffered intermittent overheating.

If you can't see where the coolant is going, then it is likely being burned, or it's in your oil pan...

In a while, I will put up some pictures of the under chassis once I get the rest of the parts screwed on. At the moment, I am having too much fun driving it. The engine is pretty clean at the moment (but those breather filters do occasionally lay down some blow-by), but there are changes in store. The carburetor needs a spacer insulation from heat for an easier hot start), and the air cleaner base will have to be replaced with a dropped, low profile base. I am still looking for an NHRA/IHRA Buick intake. The holy grail of Buick 215 intakes... Oh, and the headers, which means replacing the plumbing for the rear brakes. Don't ask... This is why I usually don't bother with "restored" cars...
But if one wants an early +8, there are not a lot of options. This one is making me happy for the most part.

This apparently never got posted back when I originally wrote it. Anyway ...

Gents - just in case anyone thought I wasn't following the discussion, I am. Present status: awaiting block check. Might not be done til next week, so until then feel free to talk among yourselves.

Now, to [possibly] repeat a couple of items. My Rover expert mechanic checked the front and rear spark plugs both sides [since they're the only ones with cooling] and none show any of the telltale "cleanness" suggesting the locus of the problem. My original [plastic] overflow tank was sealed with no vent or overflow; that's the one that blew. I've fitted a new aftermarket tank that is plumbed properly. It is NOT a nifty MG type with the option of fitting a pressurized cap regardless of pressure. The extended discussion of cap locations, pressures etc. is interesting but not relevant to my original question re: where did the gallon plus of coolant go. The temp sender is suspect but again, not a likely source of the problem. Nor is a leaking heater core though I await more info from the very knowledgeable John Willburn.

The car is not "new to me" as I indicated in a previous email. I cannot say with certainty what material the head gaskets are at this writing; I shall get the info anon. The water pump was rebuilt and, again as noted, there's been zero/no indication on the exterior of the engine or anything in its orbit of coolant leakage.

I think that brings me current. Time for tonight's debate here in Portland OR. Later, friends.

---

David P. Crandall [MSCC #4128, MOGNW, Morgan Plus 4 Club,
3/4 Morgan Group interclub/international liaison]
23 NE Morgan Street
Portland Oregon 97211 USA
www.morganstuff.com
email mogdriver@gmail.com
1971 Plus 8 [Green Meanie]

Actually, the blown header tank indicates a problem with cap pressure and/or location. Also, the possible absence of an overflow or recovery can. AND... Perhaps something is pressurizing your cooling system... That would turn up in the block test. I had a similar problem once with a Peugeot Diesel and a very small water passage head gasket leak that didn't loose coolant as much as it allowed combustion pressure to pressurize the cooling system.

Whatever... I am sure that the block test will answer the questions. And...If the block is sound, well... I hear that block weavils love antifreeze coolant. Especially the red stuff, but they like green, too. 'Shame that you have to wait so long for a test so simple as a block test.

David, So Morgan in 1971 put on a recovery tank with no vent or provision for a pressure cap? Yikes. It would work providing it was sized large enough to accommodate extra swell from an extreme overheating event. It certainly couldn't relieve enough pressure to make up for combustion gasses finding their way into the coolant. I had one of the steel shim head gaskets fail completely one cold winter night with my Range Rover. It released coolant past a gear clamp on a lower radiator hose before the pressure cap lifted on the overflow tank. I drove it into town with the pressure cap removed and bought several jugs of windshield washer fluid good for minus 40 degrees. I kept topping up with that every two or three miles and made it to my home in the country without ruining the engine. It sat with windshield washer fluid as coolant until I had a chance the next summer to replace the head gaskets and rebuild the heads along with some other work. Fred

David, Possibly another cause?

I had a car, 1980 TR7 Convertible, bought new. (Ok, stop laughing!) but it had the same symptoms. Loss of coolant without obvious cause.

I was loosing a pint or quart a day! Nothing wet, no puddles, etc. I was befuddled. It turned out the the freeze plugs expanded at a different rate than the block, when the engine got hot, and the coolant seeped out of the freeze plugs and onto the hot block. Where it quickly evaporated.

I found coolant (green) residue on the freeze plugs. I sold the car with 8K miles.

(FYI, I have my own coolant problems at the moment. Plus 8 currently on the lift with a leaking water pump.)

Cheers,
Mark

Mark Braunstein

I have had the same symptoms as well. Also with a 3.5 Plus 8 engine block. And AFAIK, all 3.5s came with the very notorious tin gaskets, though they could
have been changed later for the remedial composite gaskets. Be aware that the thicker composites will muchly lower the risk of gasket failure but they also
lower horsepower as they lower compression by increasing the size of the combustion chamber.

I am wondering what the resultant coolant pressure was with the system described..or am I confused by the David's description of it? i.e. What happens
when the coolant pressure is allowed to increase until it can blow a hole in the recovery/expansion/header tank? Surely the stress on all gaskets, seals, clamps
water pump...and everything in the cooling system will be put to a strain. They are only designed for 15 psi. Until David's cooling is pressurized normally, it will
be hard to be sure what is damaged, if anything.

And block tester kits are available at any auto store/factor. Takes a few minutes for a test..but much longer for it to sink in and the owner to believe it.

---

BTW, for those of us with these engines, the later 4.0/4.6 heads were made to compensate for the greater thickness of the composite gaskets. In other words,
the heads are effectively pre-skimmed. Use the old (or an upgraded) variation) tin gaskets, with these heads, and the compression goes up..enough for an
additional 13-15% bhp without any other modification. You merely have to accept that the risk of blowing a gasket increases a lot...but that is ok if you accept it.

I am saddened to write that labor costs in the developed world has become so expensive that entire engines are regularly tossed in this world as a matter of course.
I can tell you that changing head gaskets on THIS engine is not so difficult. I have done it in a morning and I am no pro. The parts for a head gasket replacement
are not expensive at all...depending on where you source them.

gmg

I had a brand new TR8 (West Coast fuel injected model), and had no problems with the cooling, other than that the radiator failed after 5 years. Other than that, the car was relatively trouble free, and worked quite well. I remember it fondly.
We eventually traded it for a new Porsche 944 Turbo, one of the most unreliable and expensive to maintain cars in my family's history. That said... We still have it, after 30some years of "enjoyment". Mom, even though she no longer drives, will not sell it. Anyway, I would trade it in a heartbeat for a nice TR8.

I also had a problem with coolant loss in my +8, but this was a fairly easy thing to fix. The sealing surface for the radiator cap on the swirl pot/filler was distorted. This allowed some coolant loss, recognized by white spots on my distributor cap. I replaced the swirl pot assembly with a 1.5" filler tube, with a machined cap sealing surface when I replaced the cooling fan. No more coolant loss.

My experience with milled cylinder heads is not an increase in head gasket failure. What usually happens is that the cylinder head surface has been trued, and whatever gasket you might use will last longer as it is seated on a perfect, clean surface. My preference is for Fel-Pro head gaskets. They seem to last quite well, and have good oil seals to keep all the fluids where they belong. I have built a few high compression engines, and have no increase in head gasket failures at all. One of my engines is at 11:1 compression, and the head gasket has been in place for about 50K miles.

If you don't like Fel-Pro, you can use Cometic head gaskets, which are steel shim with composite sealing surfaces. These are available in various thicknesses to adjust compression ratio. Excellent parts, but a bit expensive. I use them on all of the turbocharged or high compression engines that I build. 'Never had a failure.

The real problem is overheating and the damage and stress that it causes, not the problem of a higher compression ratio. BTW, if you are going to rebuild your engine, specify that the deck height be equalized. This will ensure that the deck of the block will be surfaced, further ensuring that the head gaskets will be seated properly for a long life.

While typical labor rates here on the West Coast are about $100/hr, the cost to replace the head gaskets, including resurfacing the cylinder heads, is reasonable if you do the work yourself. It will involve chasing some parts around, such as your cylinder heads to and from the machinist, but the gaskets and fasteners should all be available from your local auto parts store or speed shop. The parts costs are not crazy, and the actual removal and replacement of the cylinder heads is not that difficult. There are a few things to take apart, but nothing that can't be handled in a weekend of intense concentration.