- This topic has 6 replies, 3 voices, and was last updated March 14, 2008 at 12:44 am by
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I bought my dad’s ’65 Tiger (see Rants & Raves) and have engine questions. These questions come third-hand. My mechanic tells my husband what he’s done over the weekend, then my husband tells me after dinner. Add to that I don’t know much about engines — but I’m learning. 🙂 So if my questions sound silly or don’t make sense…..
My mechanic had a Sunbeam of his own for a while, and has been working on mine since December. He started with penetrating oil in the engine and it now turns very freely by hand. This weekend he did a compression test and found that half of the pistons have no compression. The other half have very good compression. Some that don’t are hard to get to (what isn’t hard to get to in this engine?). He suspects build-up or rust on the valve seats because there was gunk on the valve cover. He/we are trying to decide if we have to (or want to) remove the engine for the necessary repair work or if there is another way. He said the springs seem good, and the valves appear to move freely, it seems they don’t close fully. He knows that at least one is on an air intake valve since he could hear through the intake manifold. If only a couple cylinders did not have compression, he could start the engine and over time/detergents it would clean it up but that is not an option since so many do not have compression. Are there any tricks to removing gunk/rust from the valves without removing the head? If we do remove the head, any thoughts on the likelihood that we may have to have pistons re-bored?
Thanks for your help — I’ve already found good help on this forum and from Tiger Tom.
Lori N.
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To be sure its the valves, and not the pistons/rings, the mechanic should have poured some oil into the cylinders to see if the compression then goes up. As a mechanic I assume he has already done that.
So, moving on, assuming the problem is with the valves, they really need to come out and be replaced or cleaned up, and that requires removal of the cylinder heads. Heads can be removed with engine in-situ, but as you say, it is cramped in the Tiger engine bay.
Bu ask yourself this question: has the engine ever been reconditioned? Has the clutch been replaced? If not I would consider doing a complete engine out strip down, and get everything checked. I speak from my own experience (see my ‘Clutch Replacement Blog’ for more info). My engine looked like it had never been reconditioned in over 40 years! I am now getting the benefit, and its a joy to drive 🙂 🙂
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As with all things, it is a matter of what you want to end up with and how much money you have to spend. The cheap and lazy side of me would try some soft taps on the valves with a hammer (While they are in the closed position) to see if there is just some crud or rust that will work itself loose. I would probably just give all of the valves a little love tap and then do another compression test to see if there is any change on any of the cylinders. If there is any improvement, I would tap some more and test again. and repeat the process until it looked like the negine had a chance to start.
The second (just as cheap but not as lazy) part of me would pull the heads and take a long hard look to see if they can be used as-is with a little cleaning.
The what-the-heck-it’s-only-money part of me says to yank the motor and do an A to Z rebuild. Of course, one thing leads to another and there is a very long list of while-the-motor-is-out-I-might-as-well do the radiator, engine bay detailing, new motor and transmission mounts, brake lines, u-joints, clutch, trans bearings and seals, and on and on.
Again, it is a matter of time, money and sometimes just plain luck.
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Thank you. My goal is to be able to drive the car. I always wanted to, but then Dad met a tree on some ice before I got to driving age,he fixed it up, and put classic plates on it.
We’ll try some tapping later this week and make our decision from there. Our oldest is going to college in another 1 1/2 years, so money will be an object. My husband doesn’t quite go for the idea of spending it all so the son qualifies for aid.
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I think it is certainly worth trying everything to get the engine started, as the compression may improve with use. I have started these engines on much less than eight cylinders, so with a bit of luck, maybe?
Also try some fresh gas (old gas doesnt work so well), plus some squirts of Holts Bradex ‘Easy Start’ into the carburettor. It might just coax it into life, and it might wet the valve faces too, you never know.
Good luck.
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Got to visit the car yesterday… Six of the 8 cylinders now are working and have at least 120 pounds of pressure. He’s going to work on the last two for the rest of the weekend. We’re all more hopeful and relieved! Dad came along to answer questions about the various parts he had with the car. As the engine gets ready to run properly, some of the things next on the list are the brakes and boosters, leaky water and fuel pumps, check the radiator, and replace all hoses. Dad had rebuilt the brake master cylinder, but that was 20 years ago, and it never got put back on.
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