fresh7.4 locked up first time out
 

Two weeks ago my fresh 454 built by myself locked up on the first run after 45 min. of running time. I restarted it the next day and it seemed to run fine. I pulled it anyaways and found no problems except for the thrust area of the rear main. I brough it to the machine shop for a thourough tear down and they found nothing wrong. Polished the crank and put new bearings back in. (let them assemble this time) I never checked drive alignment when i put it back in but it slid right in place. What cou7ld have caused this? Note: the oil pressure never exceeded 40psi and i was leary about it from the start. The machine shop said everything was ok.

Define "locked-up"?

It couldn't have been locked-up/seized if it started the next day...could it?

Oil pressure does seem a bit low though. How does it run now?

As I was cruising at 3200rpm it started to loose power and i tried to give it more. Motor died and would not turn over to restart. Pulled all plugs and there was no sigh of any water. Let it cool down and it fired right up the next day. Ran smooth but had a squeal noise like the impellor was getting dry and ready to go bad. The noise was not the impellor. I pick it up from the machine shop today. The machine shop said I did nothing wrong with assembly and they could find nothing wrong except for the rear thrust side of the bearing. clearaces perfect, oil pump fine, no blocked passages. He put new bearings in and replaced the oil pump anyway. I will put the long block together myself.

What was wrong with the rear thrust bearing? I only ask because I'll be going through mine soon and plan on doing it myself as well..

Keep us posted... Good luck

The rear thrust bearing was worn into the brass/copper part of thr tri-metal construction. Only on the thrust area of the bearing.

Cheitman,
Did you check crankshaft endplay? Should be between .005-.007. If there isnt enough endplay I have seen them ruin the rear main and the thrust surface of the crankshaft. It probably restarted after the cool down process due to component contraction. Be sure to check the thrust surface of the crank before you reassemble to be sure it isnt blued or scored.
Bob

Could've been something other than mechanical, like fuel or ignition...

What were your engine temps? I'm wondering if you over heated it. I had a engine once that overheated because the thermostat stuck closed. It was running fine until it came to an idle where as it promptly stopped. The engine wouldn't turn over, the starter only clicked. About 20 minutes later the engine started and ran just fine. Also, if the engine is without water, the gauge will not show a high temp. It can't read air temperature, only water.

Endplay was and again is .006. Motor was running 150-160 and I checked manifolds immediately after the incident and they were cool to the touch.

Ring end gap?????

like US1 said, also check piston to block clearance, maybe it is a little to tight , good luck and let us know what happens

It still has stock pistons and Std. bore

I would say you overheated it too. I did it once when I put the raw water pump on backwards. I won't do that again. Luckily the motor wasn't hurt at all, I changed the hoses around and the next day everything was great.

check your distributor gear. If you put a billet cam in there it would have eaten your standard distributor gear and thrown the timing way out of whack. A bronze gear would then be required..just a thought from experience....

:( Sorry for your troubles. Just a question on end clearance and rear main install. Did you use a dead blow hammer to seat the bearing thrust surfaces when crank was installed. .006 end play was checked after all main bearings installed and torqued down? Any pictures of failed bearing and crank by chance. Machine shop had to polish or grind thrust area on crank. Did they check it for straightness? What did the other main bearings look like? Gotta make you nervous with NO clear answers why bearing failed. I know it would make me nervous :rolleyes: Sorry for so many questions.

Check the drive coupler. Make sure the splines didn't twist. Did you have to draw the drive in the last 1/8 th of an inch?

If you got a look at the water pres guage before it "locked up", that may be able to help you (or maybe the oil temp...if it was really hot). Any clog in the water line can disrupt flow and if that impellar gets hot enough it will shut the motor down. Happened to me when my water line clogged. It about gave me a coronary! I know you said the impellar looked fine, but maybe it heated up without ripping apart. Not likely perhpas, but that squeeking/squealing sound seems like that to me. Just my .02, alotmore knowledge on this thread than I got.....;)

Possible bent flexplate or maybe too much grease in the coupler splines. If the coupler has too much grease it will hydrolock and put a huge amount of pressure on the thrust bearing.

sure sounds like it was getting hot. I'd bet the squeal was in fact the impellar. What about your water pickups are they all clear? Are you sure it is actually getting water?

I still like US1's question. Did you set the piston rings to "marine" gap instead of auto? Boats run hotter pistons (always under load) and cooler blocks.

Good luck.

Thanks for all the suggestions. First, I did use a dead blow hammer on the crank to seat it. Ring gaps are on the loose side. Impellor and housing were new. I did not put too much grease on the splines, only enough to coat the shaft. the drive slid flush into place, did not have to draw it in with the bolts. When the motor locked up, I checked the risers to see if they were hot and they were not too hot to touch for a long period of time, in fact, i was leaning on them while pulling plugs and never got too hot to touch. Heres the scary part, my buddy just had a similar motor put together by the same shop (I assembled mine myself) Oil pressure was great at start up, after 30 min of run time, all pressure was lost. Even double checked with a mech. guage, only shows 5psi cold. His is a gen 5 mine a gen 6. Is there anything that could have been overlooked in the block prep? Mine is now ready to put back in boat. Was going to drop in tommorrow. I think I will wait untill I find out why his did the same.

OK, I fired the new motor today and have good news and bad news. The good news is that the new motor seems to run fine and I found the little demon that caused the problem in the first place. The bad news is that the problem was that the drive had no oil in it except for the reservoir. It was the drive that seized up and not the motor, however, the extra strain did cause the thrust bearing in the motor to prematurely wear. the new motor only ran for maybe 1 min. so i suspect no damage. I heard the growl again and found the drive dry. Question is, how mucn damage did the drive sustain (BRAVO ONE) running 30 min at 3000-3200 rpm locking up and turning again when cool. A dealer told me that the same thing happened to someone else last year and they filled the drive up and it ran fine. I dont like that idea.

No way you will be able to refill and go. The top bearing is weak to begin with and will smoke up with low lube level. You need to have it pulled down all the way and inspect it-be prepared for UGLY:(

And I was pretty close:rolleyes: Sorry about that:(

Man that is a story to remember. Glad you found your trouble but sorry about the drive. Personally I would find a GOOD drive tech and have it looked at. Bearings had to get awfully hot besides what the gears look like.

At least I have an explanation for what went wrong the first time. I did not have that "fuzzy" felling without an explanation from the machine shop. In fact, he told me it had to be something with the drive because all clearances were rught on and I did nothing wrong with assy. I could fill it up with oil and head to the river. There's lots of debris from recent storms. Aim for the biggest log and call the insurance co! I don't opereate that way though. With my luck, i'd put a hole through the boat and miss the drive. My luck is so poor, it could be raining whores and I'd get hit by a queer!

Just a fyi, years ago on a canadian fishing trip, ran a omc for one week, no problems, pull boat to leave and found the nose on the lower unit gone, 3 inch hole! Tore it apart and the bearings were hardly damaged except for the rust. Don't know how or when it happened! Figured it was the cold water that saved it!