M/V 404 Parts Help

1700 Loadstar

1700 Loadstar

New member
My M/V 404 has no compression port side #3 cylinder. After making sure all the valves were closed I put some air to the dead cylinder and had air coming out the port exhaust. This leads me to believe I have a bad exhaust valve in this cylinder. Before I tear in to this beast I would like to locate parts needed such as a gasket set and valves.

Searching the web I found Felpro HS8475PT is the gasket set I believe I will need but of course my local parts store can not locate it. Anyone know of a good parts source that might have a gasket set and new valves. I believe ebay has the valves if I have to go that route.

Any input on my situation and if I missed something in my diagnosis would be appreciated. All other cylinders are 115-125 psi and the truck is running low on power due to this bad cylinder.

Thanks

I
 
Parts for the medium duty trucks are not really available here. Your best bet is to try the IH dealership.
 
I think we can source those for you. Might want to contact our parts department and see if they can check for you. 530-274-1795
 
IH parts didn’t have the gasket set but I was able to find one on eBay.
Still at a loss! Took head off and sent it to a machine shop. They pressure tested it mag tested it and removed the valve on dead cylinder and said it checks out ok. Also looked at head gasket and stain no problems. The cylinder wall looks good and no holes in the piston. I put I the head back on with old gasket, put valve terrain back together and tested again. I still hav no compression on this cylinder but it does blow out the exhaust port. I tried 2 different compression testers. Both show compression on the other cylinder, so they are working.

Anyone have any ideas on this? Thanks
 
Put compressed air in the spark plug hole and with the valves closed, listen for where the air leaks from.
 
Thanks Chappie, I did that and had air coming out exhaust pipe. Figured I had a burnt exhaust valve so pulled the hard and had machine shop check it out. Head checked ok. Piston and cylinder look good. At a loss for why still no compression.
 
Valve terrain is going up and down as it should. Push rods are straight. I tried changing lifters but same issue. If I loosen the exhaust rocker so valve is closed I get compression. As soon as I retighten it to recommended 20lb torque I loose it. Something is off but not sure what or why.
 
Possibly a lifter stuck in the pumped up position? Can you pull the lifter and try to disassemble and clean it?
 
Chappie I have tried 3 different lifters with same result. I replaced all the lifters bout 6 mo ago due to one sticking. I tried a couple of the old lifters I pulled.
 
Ah, sounds like there's some history here. With the rocker shaft removed place a straight edge across the valves and see if the stem heights are all the same.
 
Laid straight edge, the problem exhaust valve sits about 1/16” higher than the rest. I measured all the exhaust springs with rockers loose got bout 3.4mm. Ran cam lobe down on each valve and torqued the rockers then measured springs again. All squeezed to 3.3ish mm except trouble on which squeezed to 2.9 mm. Here lies the problem unsure on solutions. I have measured all push rods they a same. Rocker pedestal same length. Tried couple different lifters with same result. Measured the valve lengths, with bad one being only .005 ish longer. Measured springs with bad on being noticeably longer, can’t remember how much.
Any ideas on best way to tackle the issue of something is out of wack causing the spring to collapse more on bad cylinder when torqued.
 
Well, 1/16" higher then the rest is a huge difference. Most likely the valve has receded into the seat or the stem is stretching. If this is what is happening you want to replace this valve before it drops the head into the cylinder.
 
Thanks Chappie, I was thinking on the same line. Valves are darn near the same length so guessing something is going on with the seat. Back to the machine shop. I’ll let you know the outcome. Thanks for your assistance.
 
Update, we discovered what we thought was growth was actually shrinkage.
When I bought the truck it had an engine tick. I opened it up and replaced all the lifters which solved the problem but the engine didn’t seem quite right. Well today I found or figured out that someone prior to me tried to fix the tick by grinding the rocker pivot down. This put more pressure on the lifter and solved the problem short term but caused me a big headache. I have been chasing my engine low power problem for 4 months.
So on to finding a new rocker pivot. Luckily my machinist noticed the pivot looks like one used in Fords. He measured one from an early 80s 302 and sure enough exact match. Thanks everyone, hope this can help others in the future.
 
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