Moss Motors, Ltd

Looking for guidance!

(AH 3000 MkIII)

I just completed a head rebuild.  I'm concerned though because on my first ride (40 minutes or so) the car is blowing huge HUGE amounts of smoke.  I believe it is primarily blue smoke (mostly).  It does not appear to smoke when coasting, but smokes some when idling and then smokes a lot when accelerating and driving.  And it keeps smokin'.  The car did not smoke or smoke very little before the cyl head rebuild.

I have read in other posts that smoke is normal at first during the break in, but I assume that's mostly with complete engine rebuilds. 

Oil pressure is fine. The car runs smoothly, but after 40 mins I could tell the plugs were getting a little dirty.  The breather tube is clean and clear.  I will test compression this week (need to get a tester) but I know from earlier testing that compression was very consistent across the cylinders before I pulled the head. 

I feel that I adjusted the valves too tightly at .012 cold for this first run and need to correct that, but would this contribute to oil burn? 

My rockers were re-bushed and the shaft had no visible wear problems, but my primary suspicion is that there is too much oil spraying around the top of the head.  Anyone have experience with a problem in this area?

I'm anxious to rule out any major problems, like rings.  How should I go about tracking down this problem?

Phil

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Austin Healey 3000 MkIII ph2, 1965
MG TC, 1949
Corvette, 1966

I don't know the AH 3000 very well, but does it have a PCV valve? My MGB does, and once I fitted this back together incorrectly, and it started hoovering oil out of the crank case and blowing clouds of smoke. Worth checking perhaps...

I'll leave other ideas to the Healy experts.

Best of luck, 

Ed

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I want my MGB

"... but my primary suspicion is that there is too much oil spraying around the top of the head."  The problem is not too much oil spraying around, but oil seeping into the combustion chambers.  I'm not any sort of engine rebuilding expert, but I'd lay odds on valve stem seals - particularily the intake valves - as a likely source.  Just my 2 pence worth!

What say you, Motorbill?  Lay your words of LBC wisdom upon us mere mortals! 

I agree with Dick Mason. If only the head was redone, then it is most probably valve guide/valve stem clearance or somebody forgot to install seals.

Alfonso 

Somebody booted the job in the area of guides/seals. The only other thing that comes to mind is the possibility that the head has been cracked in an area wherein oil can now pass to an intake port, but this isn't likely.

Run the engine in such a way as to make it smoke like crazy, then shut it down. Now, when it's cool enough, remove the carburetters and intake manifold. Check for oil in the manifold. Next, see if you can peer down the port(s) to see if there is an apearance of oiliness on the valve stems or backs of the heads. Depending on which head you have (On the engine!), you may not be able to observe this, and therefore you may have to remove the cylinder head and check to see if one or more of the intake valve backs is wet or already crusty with oil. If you find one is, there is a problem with that cylinder, but if none are particularly wet, it's likely they are all a problem as a result of machining too much clearance in the guides, or the complete lack of seals. Let us know what you find.

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Thanks Motorbill (and all),

Wow, basically start over!!  While the machine work was done be a very reputable ole timer, I suppose anyone can make a mistake. 

This is a 6-port head on an AH3000... I don't recall if the valve stems are visible through the ports.  God I hope so.  If the valve seals are missing, are these serviceable from the top of the head with the head still in the car?    It seems like they should be provided I could get a spring compressor of some kind in there. 

This may be too much to ask in a forum, but on first blush I don't understand how those little O-rings could have any significant effect. What exactly are they sealing? 

 

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Austin Healey 3000 MkIII ph2, 1965
MG TC, 1949
Corvette, 1966

Phil,

 

Did you do any of the work yourself?

Torquing the head , fitting the carbs, ???I know you said you set the cold clearance at .012.

Blue smoke-White smoke -Black smoke??

 

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Tom
59 100-6
65 mgb
70 mgb

Thanks Ed,

I was lying awake a bit last night thinking about this very issue.  There is no PVC valve, but there is a breather tube from the block to the valve cover to the carburetor. I replaced all of the hoses etc.  But there there is a T-connector in the mix that I didn't check but which I suppose could be blocked.  It will be easy to check.

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Austin Healey 3000 MkIII ph2, 1965
MG TC, 1949
Corvette, 1966

tmghealey,

The machinist completely reassembeld the head but I did the rest.  Its been a long time but I had some previous experience with rebuilds with great mentors.  I torqued the head about 3 lbs at a time (probably overkill).  I also re-checked the torque a day later before completing assembly.  All the reassembly I did was to doc'd torque specs where available.  I had the carbs out/in the car on a previous occasion and was able to avoid some of the pitfalls I had learned at that time.  Also had a lot of telephone guidance from a healey/mg shop during the job. 

The smoke is primarily of a blue tinge.  There is black smoke for only a short burst after idling at a stop, so I still need to refine the carb adjustment.  I don't think there is white smoke, and I don't see any noticable drop in the water level.  There is probably an easy way to determine if water is getting into the cylinders but at the moment I can't think of it.

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Austin Healey 3000 MkIII ph2, 1965
MG TC, 1949
Corvette, 1966

Phil,

Those ridiculous little O-rings actually do more than you'd think. They are to be stuffed down into the retainers just before you install the cotters (keepers). What they do, once in this position, is seal the retainer to the valve stem and prevent oil from running down the stem, thus "flooding" the tops of the valve guides. Without these O-rings, you can bet there will be oil going into the guides. I hope yours are in place.

There is an alternative. Go to a machinist (preferably with the head) and have him examine it to see if "positive valve seals" can be installed. These look like miniature lip type seals and push down over the top of the guides. They even have little Gaiter springs to keep them tightly sealed to the stem. The only rub is that you need to have enough clearance between the guide and the inner valve spring to allow them to fit. That's why I indicated that you'd want to bring the head to the machinist. Perhaps you could drive to the machinist and remove the valve cover there for him or her to check out the situation. There is yet another type of valve seal which might work here.

It's called an "umbrella" seal. It stretches onto the valve stem and has a deep  sort of elongated mushroom look to it. The "wall" of the mushroom just drapes down over the guide and keeps any direct access from being available to the top of the guide where the valve stem enters.

If the guides are indeed the problem, one of these solutions will surely work.

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

You are awsome motorbill!  Thanks for all the info.  I will definitely follow up with the thread after investigating the O-ring situation.  It will take me a little while to get there, but that's why we love these things so much [I suppose].

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Austin Healey 3000 MkIII ph2, 1965
MG TC, 1949
Corvette, 1966

Phil,

Wait! There's one other thing you might want to check. Most of our sports cars with OHV heads have an oil delivery drilling that opens up under one of the rocker pedestals, which in turn has a hole that leads up to the feed for the rocker shaft, but not the Big Healeys. They use a separate fitting and pipe off to one side of the shaft. This pipe then runs up to the top of one of the pedestals, from whence it enters the hollow shaft and is distributed to all the rockers. The problem can stem from the fact that at the top, the fitting is threaded into aluminum with fine threads. They often strip, leading to lots of oil flooding the area, but none reaching the rocker bushings.

Remove your valve cover, disable the ignition, remove the spark plugs to lessen resistance, and crank the engine over while observing the rocker shaft and this delivery tube. (you can't miss it) See if the oil is leaking from the fittings and indeed flooding the entire rocker area up to a level where it'll reach the tops of the guides. I doubt it, but you never know... You can even run the engine for a very short period with the cover off to really see the effect, but it'll get sloppy after about twenty or thirty seconds!

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Thanks again motorbill,

I know from first hand experience how easy it is to strip that aluminum rocker bracket.  I had to order a new bracket and after my first failed attempt to screw the banjo bolt of the oil tube into the bracket. 

Anyone reading this that is doing their own BJ8 (and probably all 3000s) head work take note:

Screw the banjo bolt into the rocker bracket and rocker shaft while putting together the rocker assembly on the bench.  Don't take the banjo bolt out until after the rocker assembly in in place (but not torqued) on the head.  The banjo keeps the rocker shaft and center bracket in the correct position.  Once the assembly is in place you can remove the banjo in order to torque the brackets.  When installing the oil tube, be sure not that the banjo bolt does not bind in the bracket AT ALL because as MotorBill points out the bracket is aluminum and will strip effortlessly.

So, motorbill, I will check the fittings as you recommend because I would like to confirm that it is not leaking, especially at the "other" end which threads onto a nipple on the head.  It was really difficult getting a wrench in there.

Meanwhile, what do you think about this theory?  The first time a ran the engine after installing the rebuilt head I noticed very little if any significant smoke.  The next day was the longer ride where the engine smoked so badly.  I believe there was a bluish color to the smoke, but it could easily have been a little blue smoke mixed w/ a bunch of white smoke (need to take a closer look at that).  My theory is that after warming up then cooling down the first time things expanded and contracted, and the new head gasket was compressed in the process.  During the second run the compressed gasket let water seep into the chambers.  As soon as possible I plan to re-torque the head. 

 

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Austin Healey 3000 MkIII ph2, 1965
MG TC, 1949
Corvette, 1966

Oh yeah,

Any time I install a head gasket, especially a big one like on a Healey six, I heat the engine to operating temperature and then shut it off and let it cool to dead ccold, overnight if possible. Then, before starting it again, I retorque. If you have not retorqued, you are inviting trouble. Try not to run the engine until you have done so. After retorquing, you'll need to adjust the valves. Let's hope it hasn't established a "path" for the oil or water, and that you can get it to seal. 

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

The proper way to test your rings is to do a cylinder leak down test,as it sounds like your rings are worn and not removing the oil from the cylinder walls properly.By repairing the cylinder head and valves you have increased the compression and the old rings cannot handle it.A simple compression test will show good but the reading will be false as the rings will be sealed with oil.Good luck