TR6 TR6 putt putt sound

[ichthos]

Ever since my last cross country trip my car has not been running like it should have. For lack of a better description, it makes a mild put put sound when accelerating, and is especially evident at lower speeds. I experience a slight reduction in acceleration power. This came on sort of gradually during the end of my trip. I adusted the valves - no change. I found there was a vacuum leak, and a tear in one of the air valve diaphragms. I repared them, but there is still no change. The linkage does stick slightly on the carbs, so it is difficult to get the timing perfect, which also effects adusting the carbs. I am getting a second pair of carbs rebuilt professionally, and I should have them back in two weeks. There is rarely one nice fix for a problem in this car. Are there any things I should be checking while I am waiting for my carbs?

Kevin

 

[DougF]

Is it a steady sound or is it random? If it is steady, you can pull plug wires while the engine is running to determine which cylinder it is. You may want to use a pair of rubber gripped pliers to avoid getting shocked. Once you isolate the cylinder, pull the plug to see what it looks like. If fouled, replace it.
Are your plug wires new?
If the sound is random, pull valve cover. Slide #1 cylinder rockers toward the back of the engine. Feel the underside of the rocker shaft for wear. A worn rocker shaft or worn rockers can cause a random miss. Rockers wear on the pads that make contact with the push rods. If a groove forms on the pad, it can be nearly impossible to properly adjust the valves.
There is a company that rebuilds rockers and shafts for a reasonable price on the left coast. Their name will have to come from someone else.

 

[Gliderman8]

Kevin- After a long trip like that, you may want to check your torque settings on the head to make sure its within spec.

 

[ichthos]

The sound is steady. If the sound is not random, can I rule out a valve problem?I forgot to mention that I did clean and regap the spark plugs. When I pull each spark plug when the engine is running, what exactly will I be expecting to happen? I haven't changed the wires since I got it running three years ago. I will go ahead and check torque settings on the head.
Kevin

 

[poolboy]

Does the car have to be moving to hear the noise ?
Can you hear the noise when the tranny is in neutral and you standing along side of the running engine, manipulating the throttle linkage ?

 

[Marvin Gruber]

AS cheap as it is, change the plugs. A Plug may look good but still not fire. I've had that problem with several cars lately.

Marv

 

[John_Mc]

My experience is limited so bear that in mind BUT I had a problem with my car sounding "sputtery" and gurgly, especially at lower RPMs but was still driveable and seemed to smooth out more at higher RPMs. Turns out that I had blown the head gasket between two cylinders. Not sure how you'd test that.

 

[Moseso]

That is the case with my TR3. Runs fine under load, though it does make that "putt" sound -- louder when accellerating -- doesn't idle on all four except before it warms up. At first I suspected a leak in the exhaust manifold. A compression test, however, showed two adjacent cylinders (3 & 4) 20 pounds lower than the other two. That would be a very convincing indication of leaking between the head and the block. The new head gasket should be here tomorrow.

Try a compression test. One low cylinder + that "putt" sound, probably = bad head gasket. Two adjacent low cylinders + putt almost certainly = bad head gasket.

 

[ichthos]

As far as the sound goes, it is most obvious at low speeds when I am accelerating, like if I am pulling out of a parking lot or from a stop sign. It is not really noticeable to me when it is idling, but my car does run a little rough. As far as the head goes, does it have to be cold to retorque it? If I end up having to put in a new head gasket, do I have to get the head surfaced?
Kevin

 

[Moseso]

No, the motor need not be cold to retorque the head. In fact, there is much discussion hereabouts of retorquing the head "hot" after a removal/replacement.

Need you have the head resurfaced? That will depend on what you find if/when you pull it off. If you've had a head gasket failure, the head and the deck should both be checked for flatness. Your shop manual will have some specs for allowable tolerances from dead-flat.

My sound is directly proportional to load on the engine. I can hear it at idle. It is louder when accelerating (any speed) -- quieter when cruising -- and disappears altogether when decelerating. That would be consistent with the notion that the exhaust of combustion is making the sound when it escapes via some route other than the exhaust manifold/pipe system. The more you have your foot on the pedal, the more noise you're going to hear.

 

[Dale]

Just a SWAG, but could be a leak at the exhaust manifold to cylinder head joint.

 

[swift6]

On the TR6, you need to remove the rockers to torque the head. So doing it while "hot" is a little rough. It is worthwhile to check the torque on the head though. While you have the rockers of, you can check the tips of the rockers for wear. Also, all twelve valves should be fully closed once you unbolt the rocker assembly. If one of them is hanging open due to some obstruction, you might be able to see that.

Lots of good advice so far. The compression test may yield some more useful information. A leak-down test would be even better but you might need to find a shop that would be willing to do it. It is a harder test to do for the novice mechanic in their own garage. It can be a pain in the rear even with a well equipped garage.

If you haven't tried pulling plug wires while the engine is running yet it could also be informative. You should expect a significant running/idling difference when you pull one wire off. If that happens, then you know the cylinder that you just disabled was making a positive contribution. If it doesn't make a change, then there is something amiss with that cylinder.

If any of those tests do indicate a problem with valves or a blown head gasket, then it is time to pull the cylinder head off. Since both the block and the cylinder head are cast iron, you may be able to get away with simply installing a new head gasket if there was no serious overheating. To be safe, you can put a straight edge across them and check them for flatness.

Lots of good ideas for you. Report back with what you find and we can continue from there.

 

[swift6]

Just a SWAG, but could be a leak at the exhaust manifold to cylinder head joint.

It could also be an exhaust leak at the manifold and downpipe. Though that should be more obvious by ear if you poke around the engine bay on the passenger side while its running.

 

[Deleted member 8987]

You might want to check out "Part Two" to see where he is on this:
https://www.britishcarforum.com/bcforum/u...rt_2#Post602046

 

[DNK]

Dave- You employed or retired?

 

[swift6]

You might want to check out "Part Two" to see where he is on this:
https://www.britishcarforum.com/bcforum/u...rt_2#Post602046

Just saw that thanks... Been a while since I've been on and was trying to catch up.

 

[Deleted member 8987]

Both.
Ran my own shop, was foreman in several until about 10 years ago when some MORON decided stop signs were not "mandatory".

I gave the toolbox (full) from my mobile truck to my son, still have the big shop roll-away.

I do....some.
As levels of whatever allow.

I keep the flatheads up and running, now have a Jaguar to occupy my time.
I can still do most without a shop manual.

Altho, with the Jag, I like to "make sure", but have discovered the shop manual isn't always right.

I do what I can.....got a V-12 running last year.
Had sat for 20 years while the owner did all the body stuff.
1941 Lincoln Continental Convertible, no less.

Ran on 11.
So, yanked all 12 sparkers, finger-tested compression, #2 dead.
Installed 11, told all the "experts" standing around to stand clear, and they had no idea.
Fired it, whatever was stuck in the intake valve went out the plug hole and bounced off the ceiling.
Installed that plug, started it, set the idle and carb, and it's fine now.

But, I cannot do that every day.

It is good to be able to do SOMETHING every once in a while.

Went on a vacation trip last year with the 99 Exploder Sport.
Got to the top of Snoqualmie Pass, wouldn't idle (working on the pass, flaggers).
Kept it going, made it to Ellensburg, found the hoses to the EGR backpressure transducer had gone bad.....hose had flipped around, hot exhaust had torched a slot in the plastic intake plenum.

NAPA parking lot, JB Quick, black tape, fixed the manifold (still fine today), bought a new transducer and temporary hoses until we got to Walla Walla, got the right hoses at the Ford Garage.

Most folks panic, tow it to the Ford Garage, and give up their vacation.
Not me!

So, retired (forcibly), but still do some.
It has been very good therapy to get onto forums like this one, and use the knowledge I thought I had lost to figure stuff out.


At least youse guys put up with me, eh?

EH?

Dave

 

[tdskip]

We are glad you are here Dave. Always good to have more accumulated experience to bring to solving someones problem.

 

[DNK]

If your ever in the Mill Creek area look me up. Could use a little assistance motivating me on my cars.

 

[ichthos]

Hi Dave. I sure appreciated all of your help. I sure learned a lot from you. Wish were closer so I could have learned how to do that valve job myself. Besides, I would have loved to have had an excuse to get more tools!

Kevin