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Head Scratcher.

wlhequipment

Senior Member
Joined
Sep 3, 2017
Messages
489
Location
Sheridan, CO
Occupation
Mechanic
I have seen a fair number of small engines where the valves returned, but slowly. But this was cranking over at hand speeds. I wonder if this could be a problem on this unit, valves not closing quick enough above a certain RPM. Sort of like valve float but due to gunk in the guides. Crazy idea I know but all the good ideas have been used it seems.
There’s nothing I can rule out at the moment, so no crazy suggestions yet :). I can’t imagine float at under 2K rpm, but granted, that would fit my symptoms. Maybe I do need to take a closer look at the head.
 

skata

Senior Member
Joined
May 10, 2007
Messages
1,541
Location
midwest
Restriction in intake, and pulling air thru crankcase, hence the smoke. Wild thought
 

wlhequipment

Senior Member
Joined
Sep 3, 2017
Messages
489
Location
Sheridan, CO
Occupation
Mechanic
So I thought I’d go to the shop this morning and play with the injectors. I’m not a fuel system expert, but some stuff I had read suggested those injectors should be cracking at 1800 not 1500. Shortly after I got there, I got a call from my wife who was singing at local service. Some a$$hat stole her catalytic converter! Right in broad daylight this morning. Are you f@@king kidding me? The super crappy thing is, if we decide to let insurance pay for it, there’s a good chance they’ll total the car. The cost to repair at the dealer is around $4K, and the car isn’t even worth $6 on a good day. Of course, I’m going to do the work. I had to stop, go home, grab the trailer and go get her and the car. She’s fine and the car’s in the shop but what a dang pisser. WTH is wrong with people anymore? Anyhow, this tractor is on the back burner until I get the car fixed up. I’m going to try to attach a pic of the lil guy.
 

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Truck Shop

Senior Member
Joined
Dec 7, 2015
Messages
16,535
Location
WWW.
Some a$$hat stole her catalytic converter! Right in broad

Sorry that happened-thieves are brazen as hell, last spring a two axle car trailer was stolen a block from
my house in the middle of the day taken from a driveway while a birthday party was going on in the back yard.
 

Truck Shop

Senior Member
Joined
Dec 7, 2015
Messages
16,535
Location
WWW.
Just since I posted the above 41 minutes ago the boss calls me.
{Do you have a file on the 2021 GMC office pickup?} No I don't, what's the problem?
{That new driver we tested Saturday--I gave him the pickup to run back to Caldwell ID to pickup
his stuff and come back. Well he was caught on video at Walmart shoplifting, the police lost him
in a chase, I need the vin# for OnStar to find the truck.--------------------------------------------------------
---------------------------------------------------------------------------------------------------------------------------
I can't help it I got to laugh-lol,lol,lol,lol,lol,lol.
 

oarwhat

Senior Member
Joined
Dec 14, 2009
Messages
824
Location
buffalo,n.y.
Just since I posted the above 41 minutes ago the boss calls me.
{Do you have a file on the 2021 GMC office pickup?} No I don't, what's the problem?
{That new driver we tested Saturday--I gave him the pickup to run back to Caldwell ID to pickup
his stuff and come back. Well he was caught on video at Walmart shoplifting, the police lost him
in a chase, I need the vin# for OnStar to find the truck.--------------------------------------------------------
---------------------------------------------------------------------------------------------------------------------------
I can't help it I got to laugh-lol,lol,lol,lol,lol,lol.

WOW
 

wlhequipment

Senior Member
Joined
Sep 3, 2017
Messages
489
Location
Sheridan, CO
Occupation
Mechanic
Well alrighty then, I had to mothball this project for awhile, but I’m back at it:


I got a chance to piddle with the injection pump this weekend. I needed space at the shop, so I brought the little tractor home. All I’ve really accomplished is, I’ve eliminated the pump itself, and put it in a good position to adjust timing a little to see if I have a fuel timing issue. All I have to do is take out one of the 3 gaskets that are now in there, and see if that makes a change. One of those gaskets at .015” should be good for almost 4 degrees of timing. That should generate a noticeable difference. If not, no matter how unlikely it seems, I think I really am looking at a valve floating issue.
 

wlhequipment

Senior Member
Joined
Sep 3, 2017
Messages
489
Location
Sheridan, CO
Occupation
Mechanic
Whelp, got some closing notes for ya. Since the pump refurb, I was back to it falling on its face at around 1500 rpm, fully suggesting messing with the pump was not necessary. So today I pulled one of those 3 gaskets I made, just to see if I can make a change. And change it did. I believe each one of those gaskets was worth 4 or 5 degrees maybe? Anyhow, now it runs smooth up to 1800. So those 4 or 5 degrees was worth about 300 rpm. I do notice a little more clatter at idle, and it starts easier as well. But it seems to be happy with the change. I’m hesitant to take out another gasket, because I don’t want to hurt the little guy, but I’m real curious what a few more degrees would do. Anyhow, not a head scratcher anymore, it was all down to a timing issue. Thanks to everyone to tried to help. Much appreciated!
 

wlhequipment

Senior Member
Joined
Sep 3, 2017
Messages
489
Location
Sheridan, CO
Occupation
Mechanic
I may have missed it, did you do the spill port timing procedure to find out what the timing is actually at?
No, I didn’t. Reason being, I don’t even see any base timing marks on the engine, and no good data is available for it. The manuals that are available are copies of copies and the quality is quite poor. So you pay 60-70 bucks for a book that looks like an old mimeograph document. It seems to like the timing where it’s at, so I’m thinking I’m going to leave it. I don’t want to advance it too far.
 

Birken Vogt

Charter Member
Joined
Nov 30, 2003
Messages
5,305
Location
Grass Valley, Ca
If it was mine, I might have made my own marks and done it anyway just to be able to know where it is at. But I did replace the injection pump on my old 6.9 Ford and just set it where it seemed good and it ran hundreds of thousands after that.
 

wlhequipment

Senior Member
Joined
Sep 3, 2017
Messages
489
Location
Sheridan, CO
Occupation
Mechanic
One more “final update”. Yeah I know I said the last one was the last one, but this really is. So after some more messing with it, I just didn’t believe my own BS, so I checked the tach. I put a photo tach on the crankshaft pulley. Little piece of reflective tape on the nut, actually, and was able to get a stable read. As the mechanical tach inidcated 1500, the engine was actually turning closer to 2500. Indicated 1000 was closer to 1800, and indicated 500 (idle) was closer to 900. So, indicated 1500 was actually pretty close to redline, and I shouldn’t have screwed with it AT ALL! Ugh. I did manage to learn a lot about these pumps, so not a total loss, but a giant PITA, to be sure.
 
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