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Think I blew a MCV gasket in the 806......


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Good evening gentlemen,

You guys were a great help last time I posted a question so I thought I’d pick your brains again. 
 

I tried hauling  manure with the 806 that I put a fresh TA in over the winter. Topped off all fluids before I went to the field, hytran was in the add 1 gal range, no biggie. I always add an extra gallon over full. Fired it back up and running at idle everything seemed to work fine, I’m holding 18 psi on the lube circuit since that’s still plumbed in. PTO speed in the field or anything over 1500 rpm I get this chattering noise like they do when they are low on hytran. First load seemed ok, thought I might be able to finish out the night. Second load I started loosening lube pressure driving back the lane and running pto speed in the field. It got to the point that I started backing down the throttle so I maintained a little lube pressure (10psi, more or less as it was bouncing all over). Limped it back to the shed and pulled the other 806 to finish out for the night. Brakes seemed ok, TA seemed to shift fine to both DD and TA, and the steering seemed to function decent. It’s been fine all spring and all summer, just baled 4000 little bales of straw with it. 
 

Without putting gauges back on to check the pressures, I’m assuming I’ve probably blown a gasket again in the MCV. I had similar trouble before I got it out of the shop after putting the TA in. 
 

Here’s my question, what causes an MCV to blow a gasket between the sections? Is it a matter of not having the bolts torqued correctly? I had shimmed the pressure relief valve when I was getting it out back together, is it possible I over did it? Is it possible one of the plates of the MCV is bad? All parts that were put into it were Hy Capacity parts for what it’s worth. 
 

Hopefully I can get it limped over to the shop tomorrow night after work and do a little digging into the problem. 
 

thanks, Brian

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I've been out to pasture 15 years now. The last 5 years of my career. I saw a number of blown mcv gaskets. Ninety percent were inferior gaskets. The difference between them and what CIH supplied was easy to see. I have no idea what high capacity or CNH is supplying now.

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Have just recently bought a set of MCV gaskets for my 806. All made in the USA 

one has CNH on the packaging. 
have had gaskets previously that were cheap. Measured the thickness of them and saw 0.010” variation on one gasket. (Not measuring over the rtv bead that is already on the gasket). That’s a substantial difference and would certainly have failed quickly had I fitted it.  The new gaskets I have now are much more consistent in thickness. 

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Did you torque the MCV bolts? Spec is 20 ft lbs on the pump mounting bolts and 25 on the rest.  

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Currently the CNH gaskets are as follows 

Blue print o seal #382336R5 - .018 thick

Orange print oseal #382335R4-.014 thick

Common to just use thick ones.

 

Ag parts   kit includes 

Thick and thins  .022  & .014 no print

These are the mounting gaskets and extra plate(some models) not the inner valve gasket.

Inner gskt CNH 382323R4 with print o seal

 

Found old ticket 1993, old gaskets from IH.....$5.

Today they are $26 & $36....😯

 

 

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Did someone get aggressive scraping the old gasket? The die grinder with the plastic finger wheel is a wonder to remove gasket material but if your not careful it will grind down the metal surface also. If the edges are rounded off that may be your problem.

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Evening Gentlemen,

 

I didn’t get time to do any work in the old girl tonight but I did get it limped into the shop. 
 

FarmerFixEmUp- I do remember torquing the pump bolts. That for sure was done. I don’t remember seeing any spec on the rest of the bolts in my IT manual, so it’s possible that those weren’t tight enough. 
 

Mark- I did the scraping on the last one, I know for sure I spent a fair amount of time with a gasket scraper peeling the old one off. I probably did lightly hit a spot or two with a buffing wheel I have for my die grinder. I don’t think I was too aggressive but human error is yet to be ruled out here. I’ll be sure to inspect the edges if I do pull the MCV. 
 

To the point about the gasket thickness, the Hy Capacity gaskets were the reddish orange ones. I have pictures of that when I was working thru getting it up and running after rolling the halves back together. 
 

Well try getting into it tomorrow night and see what we can come up with. It’s got atleast 50 hours on it since the TA job. I plan to pull the filter and see if there’s something it it first before I get too carried away. 
 

As always, thanks for the pointers. Brian

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Sure do hear a lot of stories like this on here.  I haven't put a T/A in a tractor for 5 or 6 years now, but I never had an MCV gasket blow as of yet.  I ALWAYS installed Ag Parts torques.  That's what we installed when I worked at the dealer, and that's what I used when I had my shop.  From all the horror stories on here with the HI Capacity parts, I'm glad I never bought from them.  Don't guess I ever will.  Had great luck with Ag Parts.  No reason to switch anyway. 

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Evening Gentlemen,

 

Well, I put my gauge over on to check pressures. I’m all over the board, things seem ok at cold start and idle. I sped it up to 1500 rpm when it starts to chatter. Lube pressure drops to 10 psi, clutch pressure jump to 380. Steering seems a bit chattery at that point. It turns lock to lock ok, but not quite right. Brakes seem to function fine. TA seems to shift fine, it drove itself into the shop. At wide open, lube pressure goes to 0. I let it run for 5-10 minutes to warm up a bit and come back to find it pegged out my 600 psi gauge so I shut it down. 

Any thoughts as to what to check for next Fellas?

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Just finished a Ta job few weeks ago.  Ag parts spring kit is waaay wrong for the springs for pressure regulator. Pegged my gage. Thought I wrecked Ta.

Tractor didn't like the aftermarket springs on pressure regulator valve.

Not sure about High Capacity spring kits.

Not the only one on this forum with issues with Ag parts kits. I talked to that person and he told me his story. Just FYI

Ag parts admits they are having issues with kits.

Best springs to use are oem springs. The outer is same on all. The inner on 1566&1586 is what you want. 

I ended up with stock springs and .052 shim(not 1586 inner) got me 260 psi. That's what I wanted.  That is plenty for your 806 also. I know some like more. But I don't like to do any more than what's necessary.  

Pulling guys want more I realize, but gaskets and Ta gskts get pushed to limit.

Go thru Mcv, clean it, look for debris, valves sticking, bad gaskets,  put oem regulator springs in.  20ft/lbs torque on bolts. (240in/lb)Then see what ya got.

I measured 2 different sets of oem springs.  Each spring of  each set was within .001 of the other.

So here is a comparison for ya

Outers measure 3.300

Inners measure 2.880

If you use a shim washer it needs to work so it also supports the inner spring, so it doesn't get cocked in shim /washer hole if it has one.

 

 

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Well I don’t need anything fancy, she just needs to be a good functioning tractor. I got some wheat stubble that needs the manure chiseled in. That’ll be it’s test once I get it back together. I’ll call out to Burkharts in the morning and see about some gaskets for sure and a hytran filter. I had gone thru the MCV late winter 18/19 to try to limp the old girl thru one more season before the TA job. They are a Hy Capacity dealer, I believe I used their springs on their recommendation. They didn’t want to talk IH TA’s when I ordered one. I’ll touch base and I’ll report back what I find out. 

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The spring kits are a known issue. I never know where the pressures will be when replacing them. I'd put the used ones back in if you have them or try CNH, but they're a bit pricey. Check for sticking spools too. 

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Evening folks,

 

Well I got a little time to work on this thing some more tonight. Started with the filter. Didn’t notice anything out of the ordinary with the old filter and screen. Swapped it out with a new one. Pulled the MCV next, I didn’t find any chucks of gasket blown out into the oil passages. I haven’t pulled the spools out yet to make sure there isn’t anything stuck down inside. I’ll inspect the springs once I get them out for lengths.

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Ripped the MCV all apart after work tonight. Didn’t find anything that jumped out at me, other than the one oring seemed like it was a little off and has a scraped up edge. I need to get all the gasket material scraped off yet and give everything a thorough cleaning. Measured my springs. I came up with 3.290” on the larger diameter one and 2.826” on the inner. I had 3 #8 washers I believe in it for shims with a thickness of .190”. Little short on both compared to yours 815. So my question is, being that there seems to be a lot of variance in lengths from kit to kit, what were they supposed to be from the factory? Is it a shim to fit game to where everything is kosher? 

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Yes springs need to be reworked to make your pressures right from Ag Parts. They are not the same diameter as original either at least on one of them that affects how strong they are. 

Usually I reuse one and put a new one in but shorten it but my notes arent here and I dont remember.

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Brian, the springs I show measuring  are oem  springs. Both sets of oem's that I had were black in color like my photo.

Yours look like  aftermarket to me??

The coils look bigger. Thats what was wrong with my Ag Parts kit.

I tried different scenarios with my oem inner outer with ag parts inner outer. Didn't work.

My suggestion,  go buy new ones at dealer.   1586 will get you the different inner, little more psi.

The outers are the same in all models.

382306R1 outer pressure regulator spring $24

390819R1 inner pressure regulator  spring $20

59752C1 inner 1586 pressure regulator  spring $11

 

They have way over complicated the spring thing.... there is nothing wrong with oem springs. I have done many Ta's since the mid 80's.

I have only once tried a spring kit that came with gasket set. That was just a few weeks ago.  NEVER  again!! I knew better......

My friend and neighbor down the road has rebuilt over 10,000 ta assembly's since the late 70's.  He agrees!!

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Have to admit being baffled by this one. The springs get stronger as it warms up? Pump puts out more oil as it warms up? Don't think so. Regulator sticks shut as it warms? Seems it would stick the other way. It seems to me something must be causing pressure on back side of regulator. Don't have a chart and can't remember flow that well. Excess regulated flow goes to lube. But what pressure is on spring side of regulator and where does it escape to?

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815- you are correct, those are the Hy Capacity Springs that I took out of the MCV. I wasn't able to locate the old springs that were in it. I might have chucked them figuring I wouldn't need them with new springs in it. Those are relatively cheap in the grand scheme of things if they do the trick. I'll call out to the dealer when they open this morning and have them set me out a set.

 

Snoshoe_ lol i always love hearing that i asked a baffling question. The factory I work in has a reputation of being hard on equipment, I'd assume most other are similar. Its not surprising for us to call a vendor and hear "Yeah we've never seen a failure like that. That's a new one to us." Or the infamous "We've never had an in field failure on this xyz." Bring it on down, we'll give it a run for its money lol.

Appreciate the suggestions guys

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I just noticed your steering relief valve. It is original with no notches on bottom. While it is not likely the problem. It certainly will cause gauge readings all over the place. While actual pressure may be constant. Grind notches either on valve or test fitting.

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28 minutes ago, snoshoe said:

I just noticed your steering relief valve. It is original with no notches on bottom. While it is not likely the problem. It certainly will cause gauge readings all over the place. While actual pressure may be constant. Grind notches either on valve or test fitting.

You're talking about the valve that goes up into the bottom port where you attach the gauge for checking clutch pressure, correct? If so, that is a new one from CNH. I thought about swapping it out with the old one, I also have another one I got from the local boneyard from back before the TA job. Pic is one off the internet. Just want to be clear that were talking about the same part.

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I think I need to elaborate. With a smooth bottom relief and a like test fitting. Steering pressure will push the valve down tight against fitting. When you turned wheel with gauge installed. Any oil over relief was fed direct to gauge. I am certain that is what pegged gauge. Regulated pressure is also restricted from reaching gauge. Untill a groove or notch is cut in either fitting or valve. To allow free flow of oil in and out of gauge. We will have no idea what regulated pressure really is.

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Well I got the MCV stuffed back into the tractor tonight. Need to add oil yet and hook the battery back up, project for tomorrow. The old relief valves I had in the drawer have the notches cut in them. I’ll throw one of them in and see if it makes a difference. I ended up picking up the correct inner spring for an 806 as well as the spring for a 1586. What a difference in length versus the Hy Capacity spring. For now I put the correct one for the 806 in and I’ll swap them if needed.  Unfortunately they had to order the outer spring, so since I can get into that without taking the whole MCV back off the tractor i threw the hy capacity back in temporarily. I guess I’ll fire it up tomorrow and see if we’ve made any improvements. Fingers crossed lol. Thanks again for the input 

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The coils on your high capacity  outer spring that measured 3.290 appear stouter than an oem.

I wouldn't  put any shims in.  Sure would have been nice to have an oem outer to put with your oem inner and no shims.  Get you back to a base line and go from there. 

At least its easy on 806 to get to plug, you don't have a clutch booster to deal with.

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