The Stovebolt Site Forums The Shop Area Engine Shop Heard a thump

Let me start by saying this is my first project vehicle, and I have learned tons from all of you verteran bolters on this site (including the last key fix of float needle clean-out that resulted in it starting for the first time...).

I have a 49 half ton with a 235 from 1954 and 3 on the tree that has been sitting for about 19 years. 4 of those have been in my garage while restoring it, and the other 15 were at the previous owner's covered carport. The engine has always been able to be turned by hand when i grab the fan and pull it, so that was encouraging. Over the last 3 week's I've been working on getting it to start and had success this weekend. Before it finally started, the engine had plenty of clean oil (looked like it was just poured in there), I had squirted oil on the valves, then squirted Marvel MOil in the cylinders and let it sit. I checked the compression and had poor results of 55, 61, 70, 70, 75, 75 (1 through 6), so I thought the motor was toast or was possibly in need of a valve job.

It surprised the heck out of me by starting this weekend, and even more surprising is that it just sat there putting away like "what took you so long" never missed/stumbled. Since I had fixed the brakes (because I knew I was going to take it around the block if it started) did a few test runs in the driveway and off I went for a few laps around the neighborhood. It ran fine but seemed a little week which I attributed to the lack of compression. When I got back in the driveway, it made a thump sound, and I immediately shut it off thinking I just threw the fan-belt. Looked in the engine bay and saw no signs of what made the thump. Tried to re-start and it sounded like the battery was dead, so I pushed it into the garage grabbed a beer and called it a success.

Tonight I went to check on it and decided to see if I could turn with the fan again, and my heart sunk when it felt frozen solid. The thump sound is what scares me the most, and fear the worst. Tonight I'm going to check for some obvious things like the valves, oil level, stuck starter and see if I find anything else that jumps out. I'll drop the oil pan this weekend if I have time and see if anything looks wrong.

Long story short (ha.. too late) does anyone have thoughts on what it could be? I didn't see any thump/engine seize threads, but found one about a seized re-build that is making me nervous...

Thanks!
Sulli

Try this- - - - -put the transmission in 3rd. gear, and gently try to roll the truck back and forth. Don't force it- - - - - -if something has locked up, it might be possible to roll the engine backwards a little. Watch the fan while you're doing this, and it should be obvious if the engine is moving. If it rolls backwards, try to get one full turn of the crankshaft. If something expensive has happened to the bottom end like a broken connecting rod, etc., it will probably make less than a turn before locking up in the other direction.
Jerry

Jeeze, I tried pushing it backwards in third gear and it would not budge. Fan didn't move at all.

The valves/rods looked fine and the dipstick still had clean oil in it up to the full mark. I checked the oil filter, and was shocked to find the top had a pretty nice layer of loose rust chunks and on it and the top part of the filter housing interior which has to be a really bad thing if those chunks got circulated.

I imagine that the bottom end is toast. The first thought that comes to mind is small block v8, but I don't think I can swing that and an entire new driveline.

You can probably find a 235 in decent running condition for a few hundred bucks. They are out there. That's going to way less complicated/expensive than a SBC swap.

In fact, you might even go ahead and post an ad in the swap meet forum.

A running 235 from 54 or early 55 would be virtually a drop-in swap. Later models have a different water pump location that causes some hassles with the placement of the fan, but that can be corrected by an adapter plate that relocates the pump position and uses the early style pump (like the one on the locked-up engine). A parts wanted ad here, or one on Craigslist might be a good place to start. We've got a small herd of Texas stovebolters who would be glad to help you find an engine, I'm sure!
Jerry

I like the thought of a few hundred bucks and something I now know pretty well vs. a couple thousand (minimum) I am thinking of if I were to go V8. I'm just a little leery of finding another old and tired engine that might die on me again.

I have to say that in the time it was running, it honestly sounded like it would not stop running. I loved all the rumble it made in the cab when it started rolling from a stop and the whine of the gears. The journey up to this point has been great, and I've learned way more than I expected to when I started, which is probably most of the fun. Just a lot of labor for a 10 minute joy ride (or putt I should say) where it ended up with heart failure.. Good thing is it happened in front of my garage!

I'm into researching, weighing options, making a decision and then knocking it out, so I'm sure I'll find something that works.

Drop the oil pan. You might get lucky and find something that is fixable without breaking the bank.
Besides that, we want to know what went wrong.

Yeah, I'm curious too, and will dig in this weekend and report back.

Did some searching and found a 235 nearby with 3speed that was plucked from a running 1950's sedan for $600... Looks like it has everything to make it go. Never bought a used engine before and the only things I can think of to check their health is pull the dipstick, pull the valve cover and maybe bring a battery and compression tester to see how it checks out? It has a foot starter, so it should be possible to connect the battery and turn it over, right?

Engine is locked down, won't turn either direction?

With a little tinkering, you can strap that "for sale" engine down on a forklift pallet with a couple of ratchet straps and run it. Search for a few you tube videos for examples. Just run a garden hose to the water pump inlet and run a slow stream of water into it with the fan belt removed, just enough to get a steady flow out of the top hose bib with the thermostat removed. The engine will run for hours that way without overheating. Just hotwire the ignition, plumb a can of gas to the fuel pump, and push the stomp start.
Jerry

Ditto what Jerry says, but instead of a pallet you can build one of the engine dollies described in the Tech Tip section of this forum...just leave the casters off. Works great...I've done it. It only takes about a half hour to make the dolly and it keeps the engine upright very nicely during testing.

Thanks for the tips on testing the used engines. The ones I have found so far are sitting in an old tire strapped to a wood pallet. Found a lift and engine stand for around 150, but am still trying to think positive about mine before jumping off into another engine.

Well, I couldn't wait till the weekend, so I pulled the pan tonight, and I guess the good news is that there wasn't anything that my inexperienced and un-trained eye could see was wrong. Maybe someone with more experience would have noticed something, but it all just looked normal to me. Oil pan was basically clean with no shiny shards or chunks of anything in there at all. I did find some sharp black grit that would break up if you rubbed it between your fingers (guessing that is maybe varnish?). The grit was about the size of course sand and was just a thin layer in the bottom, so I wiped that all out. I didn't spend a lot of time looking under there, but I did NOT notice any bent connecting rods or missing bits. I could see the camshaft and it was just coated in oil. Took a few pictures and I'll see if I can figure out how to upload them.

It's still stuck solid and won't budge in either direction when I rock it in third gear. I didn't try too hard but could roll it back and fourth over maybe 4 or 5 inches (transmission slop?) but the fan would not budge. I have not checked the foot starter to see if it's just jammed in the flywheel, 'cuz I'm not real sure how to check that or if it is even a possibility. What else could have made that thump sound? It was just idling in my driveway, and honestly sounded like the fan belt broke and flew off the pulleys. After it made that sound, I imediately shut it off and let it sit for about 5 minutes. Noticed it puked a little puddle of oil out of the bottom of the fuel pump engine seal, but the dipstick still said it was full. I think the puke was because it was over full from me dumping a little oil on the rockers before it started (the dipstick was showing full). When I tried to start it again, it sounded like the battery was dead in that it barely turned and just went ruh-wrow-ruh. Not sure if that was the battery, or it was just really getting itself stuck real good. I can't find any evidence of something letting go in the top or bottom. There are 2 rockers that I can't jiggle by hand any more, but that may be just because of where the engine stopped mid-stroke. All other rockers have a little play and I can spin the rods with my fingers. None of the rods look like they are bent (again, untrained eye here...) and the ones I could spin did not feel like they were going off center.

One thing I can say is that I'm pretty sure the person who invented the hydraulic car lift did so because he had to take off/put on one to many oil pans.... What a pain in the arse. I'm sure it's going to start leaking now after never dropping one bit of oil in my garage ;-D

OK- - - -next attempt- - - - -take the sheet metal cover off the bottom of the flywheel if you haven't removed it already to drop the oil pan, and use a short pry bar between the flywheel ring gear teeth and the edge of the bellhousing to see if you can move the engine that way. Also look for discolored connecting rods of main bearing caps which might indicate a bearing had gotten hot and seized up. If you can't budge the engine in either direction with a pry bar on the flywheel, there's definitely something serious going on. Start loosening the main bearing cap bolts a turn or more and see if the crankshaft frees up. If not, loosen up any of the connecting rods you can reach. Eventually you'll find the tight spot.
Jerry

Have you tried to crank it since the "thump" & "ruh-row-ruh" ? Anything from the boogeyman to a brake spring coming off can make a thump sound.
I didn't read where you had checked or charged the battery.
Brad

If the engine won't turn by pushing the truck in high gear, the starter doesn't have a prayer- - - - -even with a fully charged battery or even a 12 volt boost.
Jerry

Battery has been on a trickle charger for weeks, and I've been disconnecting it from the truck while I sort things out. It's fully charged now, but I haven't tried the starter since it stuck. Here's a dumb question, an a water pump break and lock up a motor? I think I'm going to try some more 3rd gear pushing and see what happens.

Anything is possible, but the water pump is a very unlikely suspect. You can eliminate that possibility by removing the fan belt. Another long shot would be a broken tooth on a timing gear getting wedged into the other gear teeth, but it should be possible to dislodge that kind of a jam by turning the engine backwards with a pry bar on the flywheel teeth or an energetic shove toward the rear by a couple of beefy helpers. Pretend the front fenders are a blocking sled and recruit a couple of NFL linemen to help you out! (or maybe a couple of the ladies who hang out at a biker bar!)
Jerry

Dumb question: Have you removed the spark plugs since you heard the thump?

Don't know if this makes sense, but that's exactly the way my Ford inline six sounded and acted when the head gasket leaked water into one cylinder and hydraulic locked. Ended up with a bent connecting rod. At the time it acted like someone had stolen the battery!

Tim

Haven't pulled the plugs, but that is a good thought. Maybe some more MMoil in there and let it soak?

With really low compression readings (55 in #1) could it still hydraulic lock?

Maybe the piston got stuck because the rings are bad?

Let's say I manage to get it unstuck, and can push it back more than a revolution. Should I fire it up and see what happens? I was hoping that giving it some exercise would somehow make everything seat a little better and maybe bring up the compression numbers, but I'm sure it won't be by much if any. I've checked #1 about four times and get the same 55psi...

It looks like I'll either need a new motor, or rebuild.

Bad piston rings make an engine get sloppy loose, not locked up. In order of likelihood- - - -connecting rod bearing(s) most likely. Main bearing(s) next. Timing gears(a remote third place). Sticky valves or a valve seized up in a guide can lock up an engine, but you should be able to turn the crankshaft almost two turns in the opposite direction before the same valve locks things up again. Bottom line- - - -open it up and find the problem, then decide if you need to fix it or replace the engine.

Like the slogan Sun Electric Company used to put on all their electrical test equipment- - - - -"We test, not guess!"
Jerry

Sulli.....if she's locked up,....think you need to prepare to part ways or do a complete rebuild. While you are tinkering, keep an eye out on our local craigslist for a 235. I'll keep an ear open as well if I hear of one. I've got an engine that I pulled out of a donor truck that spent some years without a head on it, so If you want to tinker with it for parts you are welcome to it when you find out what's wrong with yours if will help. No promises and may be more trouble that it's worth. The oil pan may be full of water ! I'm only keeping it on the out chance that the block may be ok, and I'll want to keep that for a while longer.

Thanks Allen. Not sure what I'm going to do just yet, but I am coming to grips with having to pull the motor.

My bet is a main bearing spun. My limited experience with rod bearings failing is they spin in the rod and usually don't lock the engine down. But they make a terrible knocking sound until they come out. One engine broke a rod in half when the rod bearing spun and locked down on the crank.

But a main bearing usually locks the engine up (especially at a low speed) and about all you hear is a "thunk" and then no more turning the engine. Had a 383 Dodge engine one time lock up as I was traveling 60 mph down the road. Main had spun and locked the engine down.

Hot Rod Lincoln gave a pretty easy way to see..... loosen the main cap one at a time until you can turn the crank....then use a prybar on the flywheel teeth to see if the crank will turn..... I bet you find it soon. Listen to Hot Rod, he's mighty sharp.

Did the engine show any oil pressure before the "thunk"?

About the oil pressure gage, I was too caught up in getting it down the road, and only glanced at the temp gage noting that it didn't seem hot. Never looked at the oil pressure... That will be the first thing I check when I run it again.
Tonight I loosened the fan belt, and noticed that the fan was still not turning by hand at all... Figured that might be GOOD news in that a water pump isn't as big a deal as a seized engine, so I put it back in 3rd and gave it a good shove. This time I had a light focused on the bottom pulley, and saw it moving backwards!!
I kept shoving and it kept moving, so I breathed a sigh of relief and turned my attention back to the water pump. Wondered why did it feel like it was totally welded in place when the belt never squealed at all on my trip around the block. Then I noticed the problem. One of the dang fan blades was jammed in the bottom lip of the radiator... A few taps with a hammer, the blade was loose and the pump spun freely (2 for 2 now...). The blade that jammed is about an 8th of an inch off of the radiator face when level with the ground, while the other 3 are about 5/8" clear of the radiator. It was making a slight tapping sound when It was idling, but stopped once it was revved or under load, so I didn't worry about it. I never imagined the fan could jam in the radiator like that.
So, I guess I was being overly pessimistic about what had happened, feared the worst knowing the compression was bad and was certain that my good luck on this project had finally run out. Well, I'm back in it now, and will see how far I get next time.
Thanks for all the suggestions and support. So much good info and experienced guys willing to help. This has been a good learning experience for sure.

Replace that fan, check it close for cracks and signs of breakage. Also check the pulley the belt rides on. Take them both off the water pump and look them over very closely. I had a fan blade break and come apart one time. Luckily no one got hurt, but could have if they had been leaning over the fender with open hood and engine running. Also, check the input shaft of the water pump for bad bearing that may have let the blade wobble around.

You should consider swapping to the earlier model water pump that places the fan centered on the radiator. It requires a conversion plate that Pre 68 Dave sells on Ebay, and drilling and tapping two holes in the front of the engine block. It allows the 216 and early 235 water pump to be used on the later model block.
Jerry

Both good ideas. I have to admit, looking at that exposed fan blade whizzing around when it was running didn't make me want to hang out anywhere near it. Never thought about the fan possibly being damaged enough to fly apart, and don't want that to happen even with the hood closed... New fan is cheap insurance.

While you are at it check the radiator bracket. Make sure the radiator is not falling due to a rotted support. Maybe you already have but that was a problem i had at one point the baffled me for a bit. Glad you are on your way again.

I pulled into my in laws house two hours from where we live one Christmas eve and my 235 was "knocking". It was late at night so we checked it the next day and found the pulley behind the fan had broken and was making all the noise. The day after Christmas we were able to find a pulley and get back home

I had a "heard a thump" moment on a startup after installing a radiator in front of a brand new 350/TH400 in my '49. Engine locked up solid. Couldn't budge it with a breaker bar on the crank snout bolt.
The flex fan hit the transmission coolant lines. DOH!

Glad to hear I'm not the only one with fan/radiator issues.
When I brought it home from the previous owner, the front clip was disassembled and I had no idea the radiator support could be moved around until I started installing the sheet metal recently. Once I had the front clip in place and loosely tied together, I found that if I loosened the radiator support bolts, I could wedge a 1x4 between the bottom of the support and cross member to lever the whole clip up and down pretty easily with one foot while I pushed it around to align with the hood (all fender bolts were loose when I did this). The radiator supports look pretty good, but my inventiveness may not have been the most exact science in terms of fan/radiator clearance. Fenders and hood look good together though.

Sulli, are you back up and running? There's a 235 for sale in Beaumont that showed up in my emailed search results.

http://houston.craigslist.org/pts/6249430723.html