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MG TD TF 1500 - Smoke of smoke on startup

Title supposed to read, (PUFF OF BLUE SMOKE ON START UP)! I get a puff of smoke on start up after the car has been run at speed and sets for a couple hours, disapears when running. Valve guide seals? PJ
PJ Jennings

Sounds a bit that way Paul
If it still has the original little 'O' ring type seals they're easy to test/check
willy
William Revit

I would certainly suspect valve guides before anything.
Steve Simmons

When the engine was rebuilt there was no mention that the valve guide seals were changed to another type, so I'm assuming they are of the original O ring type. I'm going to put some oil in the top washers and see how long it takes for them to leak down past the collets, which some probably will. I'm not worried about it, I'll just put up with it until the cars put to bed for the winter and replace the seals. I don't want to change the design of the seals, as they were fine up until the last time out. PJ
PJ Jennings

It'll be interesting to see what happens with the oil on the collets/keepers---By rights if they're ok you shouldn't loose any oil at all if the O rings ok
And I think the same as you--nothing wrong with the original design
William Revit

PJ, when you say"when the engine was rebuilt", I assume another shop did the rebuild. Thus, I would speculate that they did not install the seals correctly or perhaps they didn't install them at all.
Lew Palmer

Last night I checked the valve seals for leakage. Found the 1-2-& 3 will leak down overnight to zero oil in the upper washer, and number 8 will leak down to zero in 2 hours. 4-5-6 & 7 don't leak down at all. Naturally, I'll replace all the seals. I'll order 2 sets in case one gets damaged during installation. Here's a picture of 1-2-and 3 in the morning the second picture is number 8 after 1 hour. The rest still have oil in the washers after 3 days of setting. PJ




PJ Jennings

Yep, well there it is--
Interesting that it's been ok up till now though.
It's unusual for the O rings to fail if they're fitted correctly as they are wedged into place by the taper in the cap-
How much work has the engine done since it was reco'd
William Revit

Not much Willy, It sets much more than it gets run. Only a couple of Brit shows around here and I just don't drive it that much. The wife can't take long drives in it due to health problems and no other Brit car owners within 60 miles to go on trips with. But, I love the car and get enjoyment just tinkering with it! Never had this problem before but installing new "O" rings will hopefully fix the problem! I just ordered 2 sets, just in case one gets damaged during installation, and a set of new rocker lock plates. Paul

Oh, I forgot the torque settings on the rocker bolts, do you have them on hand?
PJ Jennings

torque the large rocker stand bolts to 43 foot-pounds, the small ones to 19 foot-pounds (published torque values are wrong)
From Tom Lange
Len Fanelli

Thanks Len, much appreciated! PJ
PJ Jennings

there are a few tips on seal replacement without damaging the "o" rings while the head is still on the car.
Try archive title list "valve stem oil seal"
Ray TF 2884
Ray Lee

Thanks, Ray!
PJ Jennings

It'll be interesting to see what you find--
The most common one is incorrectly fitted O rings down the stem instead of trapped by the cap
Also, not as common but i've seen it a few times is having the oil shrouds on the bottom instead of the top causing an oil well to feed the guide/stem
William Revit

Hi Paul, Whilst I can understand the difficulty of not having a local MG minded soul I find that the intrigue of besides membership of MG clubs having joined a club of multiple car marques is great. Besides the activities our club https://tamar-historic-transport-club.square.site/ offers it's an opportunity to create friendships with those enjoying older cars. Even the experience of driving some. Perhaps you have something local to you that may provide you with that same opportunity.
JK Mazgaj

Well, found out that my overhead valve spring compressor will only grab the outer spring, any tricks to grab them both? PJ
PJ Jennings

Hold the valve in place with air pressure and your
spring cap will compress both springs. Tension and then tap the cap to free the collets.
Ray TF 2884
Ray Lee

Thanks Ray, never took them apart with the head in place, always on the bench, but no way do I want to disturb the head if I don't have to! Thanks again for your input, duly noted! PJ
PJ Jennings

forget that last post, it won't.

Ray
Ray Lee

In the "valve stem oil seal" posts are pictures and dimensions of an in situ spring compressor I made. Works a treat with compressed air holding the valve in place.(in gear handbrake ON or it runs over your foot!!!!!)
Ray TF2884
Ray Lee

If you've got one of those wind up claw type valve spring tools it's almost impossible, the claws aren't long enough to reach the inner spring--I extended/welded mine so they're longer but it's a real juggle to get them in there
The springs aren't all that strong but they are long
I've removed them by compressing the outer spring with the tool and then manually squooshing the inner down by pushing down on the tool but very messy getting it back together like that-
You can do it by using your 12" shifter(it needs to be one with a largish hole in the end of the handle) on its flat with the hole in the end centered over the stem then drill a hole in the handle in line with a rocker pedastol bolt--then use the shifter as a lever to compress the spring----You need to use the larger/outer pedastol bolt otherwise you won't get enough travel to release the 'long' springs

and plenty of rag covering those pesky holes waiting for the collets
William Revit

Ray, I downloaded your spring compressor, the one in use, and the picture of the dimensions. Thanks for posting the photos! PJ
PJ Jennings

the photo shows a flat handle. It needs to be cranked up to clear the carbs and the side panel on a TF.
There is also a tip for fitting the "o" rings
Ray TF 2884
Ray Lee

My very simple spring compressor I made up and it works perfectly! The Center hole is oversize to allow up and down movement fore and aft without binding. No need to have a second person to hold anything. Using the large rocker tower bolt hole and double-ended stud. I do place a soft rag under the tail of the tool so no scratching occurs. PJ
Oh yeah, 90 lbs of air pressure in the cylinder keeps the valve up tight!








PJ Jennings

Great solution to renew the oil seals, wish I had thought of it!
I have had my TF for 50 years and the original "0" rings have always worked fine when correctly fitted.
Ray TF 2884
Ray Lee

Used the soda straw trick and it works very well with no seal damage using a generous amount of oil on the straw and stem. 4 done so far, washers filled with oil, and no leak down! I will say that, other than # 8, they didn't look too bad, but of course, they all get new seals. PJ

PJ Jennings

Well, I replaced all the stem seals and after setting for 24 hours with oil in the washers, there were zero leak downs past the new seals. The tower shims shown on the head are for a rocker-to-stem profile adjustment with the Crane cam. My homemade valve stem tool worked a treat and made the job so easy! PJ



PJ Jennings

Good result Paul, I'm a bit disappointed you didn't use your 12" shifter but you're forgiven.

I think some machine shops think all these O rings are the same and fit rings that are too small in section to seal properly----the one on your straw there looks nice and chunky so should be good.
Were the old ones smaller just by chance--?
William Revit

The old ones Willy were a little smaller in thickness but were still very flexible, they actually looked like they were made out of flat stock versus an O ring but possibly compression under the collets made them look like that. The tool I made works very well and made the job very easy. I do put a pad under the foot so no scratches. I could have made the foot to go inside the valve cover lip, but it would possibly have raised the stress on the bolt to its limit and I didn't want to do that! Just torqued up the rocker bolts and checked clearances, all seems well. Few things I have to do before starting up, like changing the oil for one. Have to put the bonnet back on then it's off to the races! LOL
PJ Jennings

Hmm--if they were in fact flat section they would have been the wrong ones--still being flexible as well as square section sounds like they were wrong-
Hopefully you've got a win-
The old Holden six's and v8's here had the square section rings and probably Chev's over your way so most shops would have them and tell you they're ok but I used them on an MGB once and they were ok for a little while, they must have only just been sealing but after a few runs same result as you had---smoke

William Revit

Willy, I still have the old O rings, I'll look at them a little closer and maybe I can get a decent picture of one. They don't look like a normal O ring though! Paul
PJ Jennings

Willy, here are the O rings I took out with the sharp edges. They are definitely not the same! Paul




PJ Jennings

With the new seals, there is zero smoke at startup and anytime! Time to set down and have a nice cold one! Grin. PJ
PJ Jennings

Nice job young man---
They look very much like Chev seals and not very good ones at that----as you say they look like they've been cut off a length of tube---the original chev seals were square section like that but a bit fatter around the middle, slightly curved out ,but still too small in section for an MG

enjoy your beer
cheers
willy

pic. of an original chev seal

William Revit

This thread was discussed between 13/05/2023 and 24/05/2023

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