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TR2/3/3A Motor knocking at start up?

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K

karls59tr

Obi Wan
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Hello all I'm hearing a loud knocking when I initially start the TR3 in the morning. It goes away as the motor warms up and I push the choke button in and rev the motor. The car runs fine once it is warmed up. Oil pressure seems OK but I cant really go by the oil pressure gauge because I haven't resolved the issue of the gauge reading high. It always reads 50 to 70 psi even at hot idle which must be too high from what others have said about their gauge readings.
The motor was rebuilt about 15 years ago and I put maybe 600 miles on the car every summer. I did recently go on a 200 mile trip only to discover that the brake caliper pistons were sticking and the motor was running really hot. 🥵Wondering if the excess motor heat has caused some internal motor damage? Any thoughts?
 
I recommend that you pull the sump and check the thrust washers. My TR3 was doing that and I waited too long to check the thrust washers and ended up totally losing a thrust washer thus causing a problem on the crank shaft where the rod was loose.
Bob
 
You could get a cheap oil pressure gauge from one of the local parts stores and connect it at the connection by the battery. That will give you a second opinion on oil pressure.

David
 
DavidApp said:
You could get a cheap oil pressure gauge from one of the local parts stores and connect it at the connection by the battery. That will give you a second opinion on oil pressure.

David
Click to expand...
Is this an easy connection to make or do I have to connect with special fittings?
 
Karl, I don't recommend that you depend totally on oil pressure to determine the condition of the thrust washers. The oil pressure on my TR3 gave no indication of a problem before I had the rod problem.
Bob
 
Thrust washers should not be the cause of this problem. To shadetree check them, push in the clutch when the noise is there. This will force the crank forward and temporarily take out any back and forth motion of the crank. If the noise stays on pushing in the clutch, this kind of eliminates thrust washers. Is what you are hearing more of a knock or a click. It is normal for the valve train (rocker arms) to click when cold and quiet as the engine warms up.

Bob
 
bobhustead said:
Thrust washers should not be the cause of this problem. To shadetree check them, push in the clutch when the noise is there. This will force the crank forward and temporarily take out any back and forth motion of the crank. If the noise stays on pushing in the clutch, this kind of eliminates thrust washers. Is what you are hearing more of a knock or a click. It is normal for the valve train (rocker arms) to click when cold and quiet as the engine warms up.

Bob I've taken to pushing the clutch when I start the car so I guess that eliminates the thrust bearings. It's a knock and I can hear it above the valve clatter but it dosn't last long....maybe it's just general engine clatter?
Click to expand...
 
As far as I remember the line screwed on where the copper line connects to the flexible hose at the rear of the engine. Checking my spare parts it just screws on the flexible hose.

David
Oil pressure gauge.jpg
 
A knock when cold that goes away when warm is often piston slap...the first sign the pistons are getting worn.
 
That is what the guy must have heard on my TR3A when he took a look at it at the Car show in Columbus. I told him I had replaced the rings but not the pistons or liners as they appeared good.
He said that he always does pistons and liners now when he rebuilds the TR engines.
TR4 pistons and liners may be on the Christmas shopping list.
Having driven the TR3B that I was working on I noticed it seemed to have more go than mine.

David
 
CJD said:
A knock when cold that goes away when warm is often piston slap...the first sign the pistons are getting worn.
Click to expand...
That makes sense because when I had the motor rebuilt years ago I only had the rings and bearings replaced but not the actual pistons and liners. Is it possible to get a few more years out of the motor before serious problems occur? It still runs fine after start up and doesn't knock every time just on cold start up. I know I'm postponing the inevitable but would like to get some more driving time in before a rebuild. Wonder if a heavier grade of oil than 20W/50 would minimize piston slap?
 
It will run for a long time like that. It's mostly an annoyance because it will get louder, but it's not likely to result in a total failure. Try straight 50w to see if it helps.
 
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