Rebuilt engine hard to turn over, but then loosens up?

[unioncreek]

Both rod caps were over torqued to 150 in-lbs. I know what you mean now by making sure the rod caps were put on right. Figured out what marks you were talking about. I have been putting them on correct. I marked the caps as to which rod the belonged to as soon as I removed each. And I always put the cap on the rod as soon as I have the piston out.



Bob

 

[shadetree#1]

In my statement, put the rod caps on correctly per the mark is a from the Service manual page that I posted previously.
On older equipment the rod caps were actually numbered from the factory as to orientation and even the cylinder number.
I always put witness marks on rod caps and stamp the cylinder number on the cap and the rod.

Good catch before something exploded, on it possibly being a rod/crank fit issue. Gets costly now days doing a standard ring re-placement on those engines. I have a OHV twin that runs really good but consumes lots of oil due to someone leaving the breather tube disconnected from behind the carb and the engine sucked lots of grit inside during use. When the breather tube is not re-connected the air intake is right into the carb throat, no filtering.

 

[unioncreek]

I was going to stamp the number on the cap, but since they were aluminum I was hesitant. I did use my machinist scribe to put the number on though. I've built quite a few auto engines in the past, but it's been a while on a lawnmower engine. I should have purchased a service manual right away. I'm going to get measurements on the crank and rod this afternoon.

Bob

 

[unioncreek]

Do you happen to know what the service manual number is. I'm going to buy one?

Bob

 

[Scrubcadet10]

according to the briggs website that model # is an Intek V-twin

https://www.amazon.com/Briggs-Stratton-273521-V-Twin-Repair/dp/B002WNZY6S

 

[unioncreek]

Thanks.

 

[StarTech]

P

Do you happen to know what the service manual number is. I'm going to buy one?

Bob

PN 273521. But you should find it online or a have member here to send you copy. I know at least 4 members that has access to the PDF copy. Besides it is much to search the PDF than the paper manual.

Working uploading to https://www.manualslib.com but that take a few days at least and their approval.

Currently someone has a 273521 listed but it is not the correct manual as it is for an Intek single engine.

 

[unioncreek]

I removed the crankshaft from the engine block so I could more accurate measurements. Both journals on the crank measure 1.498", measure each at 90 degrees from each other. I only have a set of snap(telescoping) gauges to take measurement on the rod/cap, as you can see by the measurement there not accurate. Used the same micrometer to measure the snap gauges as I did the crank journals. I took three measurement on the rod/cap #1(problem one) 1.497, 1.498 and 1.497. Put the #1 rod/piston on the crank and torqued to specs just for the heck of it and it was tight. #2 rod/cap were 1.497, 1.497 and 1.497.

I put the #2 rod/piston on the crank and torqued it down it moved firmly on the crank journal on both #1 and #2 spots. I'm going to buy a new rod/cap tomorrow.

Wish I had an inside micrometer for the cap/rods.


Just for curiousity, I going to plastigage both connecting rods now that I've taken the crank out.

I did find the right service manual as a free download using the B&S part number.

Bob

 

[shadetree#1]

Plastigauge is your friend in this instance, when used correctly.

Now: The engine was running ok before teardown. what caused the change? (maybe rod cap distortion due to torque or ???)
You need to check and keep a heads up on the end play of the crankshaft. I check crankshaft end play before taking them apart.
I keep crankshaft end play to the bare minimum specs.

 

[unioncreek]

The engine ran good before teardown. But, it was using a quart of oil in less than two hours of mowing. I believe over torquing the caps caused the problem with the #1 rod/cap, but why didn't it cause a problem with #2. I found a Starrett (first one was a no name) snap gauge and another micrometer for comparison. I wish I knew what the original diameter of the crankshaft journals were for comparison. I'm going to plastigage the rod/caps tomorrow. Just wish I knew why the crank journals measure at 1.498 and the #2 rod at 1.497 and it still moves on the crank when torqued down.

Hopefully tomorrow when I plastigage them I can figure something out.

Bob