View Full Version : TR6 Latest compression test

09-02-2015, 05:10 PM
My car is beginning to oil smoke on long downgrades. Valve job was done in 2013 and car not driven much since. Tested my compression today for the first time since before the valve job. Here are the results, starting with #1 cylinder at the front of the engine: 145,110,85 (the cylinder with the broken valve spring in 2013), 126,124 and 143 (with a wet plug). With the exception of #6, all plugs were dry, brownish gray to light black and all had held their .025 gap. In 2012, the readings were 170,162,165,155,155 and 165. In 2013, just before the valve job, the readings were 125,120,0,115,100 and 125. The valve job definitely helped but now 4 cylinders are below par. I injected some oil into #3 and the compression went up to 155 so the rings are undoubtedly shot.I probably should have replaced the rings when the head was off...but didn't. Car has about 104K miles and thrust washers were replaced in 2012 but all bearings are original and there is about 65-70 lbs. of oil pressure when cruising. I use 20W-50 oil. It was down a quart. Now my question is this - how long should I run this before replacing the rings? How about the rods and mains? Replace or leave alone? Bear in mind I will have to farm this work out as my local TR6 expert may have retired. Except for the oil smoke, the engine runs perfectly and pulls strongly. What else might need replacing? What would you do?

09-02-2015, 06:43 PM
PDPLOT, How about a over the winter rebuild. Did anybody check the grove at the top of the cylinders when the head was off? The oil pressure is very good, but replacing the bearings would be a good idea and as all will be apart , why not.
Sorry to hear your troubles, but get it right for the next few years or longer.


09-04-2015, 09:59 AM
Been there and just coming to, hopefully the end of my engine rebuild. Not cheap, but hopefully will last for a long time.


09-06-2015, 12:01 AM
Don't remember if we checked the cylinder grooves or not but I don't remember any obvious problems.
I was hoping for a few more responses and practical suggestions since we have a shortage of qualified mechanics around these parts.

09-06-2015, 09:48 AM
Given the 104k mile number, I'd say your smart money is a winter rebuild. You've got 30-60 days of driving left, run it out and just keep a weather eye on the oil pressure. As you noticed your rings are shot and will need replaced, given the age of the engine I'd guess your in for having cylinders bored which means new pistons. While your at it, have the crank surfaced or ground depending on what is needed and have everything that rotates balanced. Replace all the bearings with proper oversize ones once the crank is ground. Take a good look at your camshaft wear and tappet wear, I would guess your in for new tappets. Another item is your rocker shaft, this can cause rapid loss of oil pressure if it reaches a certain point of wear. You have reached a point in this car's age where it needs a full rebuild. Any decent machine shop can perform the required work, there is nothing very special. If you have a shop manual you can assemble the engine yourself. I would budget 1500-2000 depending on what your shop charges for the jobs.

09-06-2015, 12:23 PM
Thanks for your input. I was hoping to escape without a complete teardown. To take this car to a "restoration shop" around here would cost an arm and a leg and the car would probably sit for a year while they worked on Ferraris and Aston Martins. They don't call this the Gold Coast for nothing.And at age 81 3/4 with a bad back and potential hernia, my heavy lifting days are over. I can barely lift the road wheel back onto the splines. I'm strictly limited to tuneups these days. Old Age is not for cowards and sissies.

09-06-2015, 06:19 PM
I didn't read anything that spelled 'catastrophic engine failure'.
Maybe it's not in perfect condition, but there's no reason you can't keep driving.
Keep oil in it, don't 'drive it like you stole it' and it'll probably last as long as you.

09-07-2015, 12:27 AM
Thanks, Poolboy. I feel the same way about mechanics as I do about doctors and hospitals. Except for checkups and minor repairs, I try to avoid them unless absolutely necessary. TRs like mine are not worth very much as yet, if ever. It's clean and rust-free, everything works (except the dash rheostat) and I've had 21 years of fun - it owes me nothing.

09-07-2015, 09:55 AM
+1 for driving it unless the oil consumption/smoke becomes an issue. I used to worry if oil pressure and compression numbers were stellar. Not sure how many miles a year you put on her but she may be OK like that for quite a while.

09-07-2015, 06:35 PM
A little over 5,000 miles in 21 years. And never in the rain or in winter. Still has original seats but driver's seat has a crack or two. Tach and speedometer are not too attractive. I'll try to send a picture. I liked the TR3 instruments better.

09-08-2015, 07:41 PM
I agree, keep on driving; even if the motor gives out entirely, if necessary, you could get a replacement old motor fairly cheap and have that installed.

09-10-2015, 02:28 PM
Makes more sense to me. Why look for trouble. 20W/50 oil is cheaper than a teardown.
Thanks for the input. It's appreciated. I'll still try to upload dashboard picture. I'm not too good with this here newfangled computer stuff...