The Stovebolt Site Forums The Shop Area Engine Shop bad valve...help

I drove the truck to my place in Maine about 100 miles north. She ran good for about 75 mile then I noticed a loss of power...it was subtle but definitely real.

At a stop light I noticed it was running rough at idle. I was in the middle of nowhere so I finished the drive and when I got there I checked the compression. Just as I had suspected the #4 cylinder (which was low after the rebuild) now only has 28 lbs of compression.

The engine runs the same if the #4 plug wire is disconnected.

I removed the valve cover and rotated the engine and can see the #4 exhaust valve is jumping as it closes. It kind of pops to the left slightly

The engine is still under warrantee (I am getting concerned that this will be the 2nd time the head will have to come off. I am wondering about the quality of the work done)

I called the shop and they said to bring it in. Of course it is 100 miles away so the tow will cost what a valve job would anyway.

My question is ...is there anyway this could be something simple? I am thinking valve or valve guide or valve seat replacement...not so simple.

I am concerned that these guys are constantly trying to put the blame on something I did...I am not an experienced mechanic but I am not dumb.... I know the engine did not overheat...temp and oil pressure were fine the whole time.

Any thoughts are appreciated.

Find another shop, even if you have to pay them to rework the head. If these guys can't get it right after a couple of tries, it doesn't matter how much the job does (or doesn't) cost. Putting icing on a turd doesn't make it a cupcake! It sounds like their quality, or work ethic just doesn't pass muster. If that valve seat is damaged, or the guide is worn egg-shaped, it's going to take some machine work that goes beyond the average valve job.
Jerry

Jerry
That is what I am afraid of. This engine was rebuilt and "we did everything it needed to run right" so far I am not impressed.

I dropped some real cash on these guys and I think they think I can't tell the difference if the engine runs right or not. I asked if they replaced the valve guides an they said they were fine...they die replace 2 seats.

I can't think of anything that would make a valve jump like that but a bad guide or a bent valve. But why all of a sudden. The compression in that cylinder was just a little lower than the others when I first tested it...but the engine only had 50 miles on it and I figured it might just be a break in issue.

Really [censored] at this point ...I missed the 4th of July parade and I will miss my regular shows this season.

Rich

Sorry about the censored comment ...I did not realize that was word was unacceptable...my apologies

There is a chance the valve did stick in the guide and is bent. I think it rather slim, but if they did work on the guides, they may have made them a tad too tight and the valve could have stuck.

I'm with Hotrod. Need to find another shop.

Is the bad valve one of the ones where the seat was changed? I had a really bad experience once with a Plymouth Roadrunner 383 when a replacement valve seat came adrift on a dyno run and wrecked a piston. It turned out that the press fit on the seat was not sufficient to hold it into place, and when it came loose it broke up into pieces in just a few cycles of the valve. We salvaged the engine, but one cylinder head got trashed and a piston with lots of custom work and special balancing had to be replaced. My fault- - - -I mis-read the micrometer by a couple of thousandths when I counterbored the hole for the replacement seat! Those mistakes can get expensive!
Jerry

Roy

They said they did not work on the guides. They were reported ok

Jerry
That is what my brother suspects is that the new seat is ajar and when the valve closes it can't seat straight. I am not sure which seats they replaced I do know that when I took the head apart this valve was difficult to remove. Once I got it loose with wd40 it would move only so far then stick.

I told them that this valve seemed problematic ... That did me a lot of good

I am still trying to get the truck towed from middle of nowhere Maine

Rich

Boy Rich, I've been following these threads about your "rebuild" and nobody likes to say this to someone. But I think you really got the shaft on that engine rebuild. It really sounds like these guys haven't got a clue as to what they were doing. If it were me, I'd write it off as a REAL BAD experience, take the hit on the money that they stung me for and turn them in to the better business bureau. Then find a shop that had a good reputation and have it gone over before my head and block were completely ruined.

I've had heads done at two different shops, both costing about $450. For that money they baked and bead blasted the head, they Magnafluxed the head for cracks then pressure tested it, milled the surfaces, installed all six exhaust seats, replaced all the valve guides, checked the spring pressures and replaced all the valves with new valves and gave me back the old parts in a box when I picked up the heads.

I take the ball from that point and do my own installation and adjustments. That was about eight thousand miles ago, the situation was right to pull the short block this past winter and I had the same machine shop do the block. And they again, baked the block, bead blasted it, checked for cracks, checked the line bore, bored the cylinders .020” over and fit new aluminum pistons, reworked the rods for insert bearings, installed new cam bearings and freeze plugs of course, ground the crank .010” under and resurfaced the flywheel then balanced the whole rotating mass. Since all they do is rebuild engines I let them do the easy part also, i.e. drop the pistons in, bolt the crank back in and adjust the bearings. And again, I take it from there and do the installation my self. While the block was being rebuilt I disassembled the head which they had previously rebuilt to clean it up just to make sure nothing was askew. Cost for all of the work on the short block was about $2500. So for about $3000 total I’ve got a brandy new engine.

I got side tracked for the last 6 months but got back on the main line the last couple of weeks. Here are a some of pix of where I’m at this week. Look to the bottom 10 rows of this album (no ads, just pictures): http://www.pbase.com/dennygraham/under_hood&page=all
Denny Graham
Sandwich, IL

Denny

That is where I wanted to be at this time

These guys have engines all over the place in their shop. They seem very busy. I took that as an indication that they did good work.

Since most of the guys we used to use for engines back in the day are retired or dead I check with the BBB and the Chamber and they have no complaints.

I really believe the head gasket leak was a fluke. I have read many posts recently regarding 235s with leaks on the spark plug side of the head.

The valve is another story. I do think they charged a full price and then did the minimum to get the engine out the door.

I will give them the chance to fix it because a want to spend another $450 on this like I want a root canal. Besides how else can I get my money's worth out of them

If I am not happy after this I will take it to another shop

I did consider assembling this myself but relented as their assembly came with a warrantee ....otherwise I would really be shafted (not to mention I have not assembled an engine in many years and don't have all the tools anymore)

Everything I have done on this truck I did myself and am very happy with the truck. The one thing I job out and I get jobbed on it.

I am afraid I will never be comfortable with this engine I will always be waiting for the next problem.

It turned out had a bent push rod. When I picked up the truck after the head issue there was a slight tick when I started it which went away after 10 or 15 seconds. I am told that was a sign of a bent valve.

I think in adjusting the valves I (or the shop) may have bent the rod and not realized it. The truck runs good now again...Shop adjusted the valves and I adjusted the carb. I will do a compression test in the weeks to come to see what that reveals.

My question is if this happened once can it happen again? What really causes a bent rod? Did I tach out the motor and do this damage or was it caused as I suspect during the valve adjustment.

Rich

A sticking valve is the most common I've heard of, at least that's what got me. It's possible that the push rod was already slightly bent when the engine was rebuilt. If a guide was a bit snug it may have been just enough to finish the job.

It sounds to me like you may not have enough stem to guide clearance. The older engines required more clearance than modern engine because fatter stems expand more than modern stems. When I do valves, I mike the stem and then use a ball type small hole gauge for initial check of the guide. I then use a TESA holtest with a setting ring for a final measurement after I ream the guides. I give them the maximum clearance from the spec sheet which is kind of contrary as to what is done these days. But I don't have stems to seize. When stems seize, push rods bend, and even worse, valves can hit pistons.

Tiny
The push rods are new but I think it is possible I might have tightened the valve too much when adjusting however I am not sure

The real problem is that this is the valve I had trouble removing and that is just too much coincidence for me. I am sure as crenwelge said that the clearance on this valve might not be sufficient at high rps and high temps to move like it should. I will keep driving it and baby it s little to see what happens

Crenwelge
I am sure you are right as I understand the concepts you mention but have not a shred of expertise to carry out the task...which is why I relied on a professional

I am sure I have not heard the last from this valve

Thanks for the advice
Rich