[Mac_Muz]

Hello all, I am Mac.. Muz is because all Mac's have been taken about everywhere and I shoot muzzeloaders. I am called Mac in real life, short for McKay. My first name is Bill, which gets me into all sorts of problems at historical events when 30 other guys named Bill are in ear shot.

I live in Ossipee NH.

My truck is a 84' K-10 1/2 ton 4x4 with working auto hubs no less.

I bought this in 87' and used it hard up to 99 for everything. I broke the 700 R4 tranny in 99 plowing snow. The planetary carrier was smashed in large hunks, and the gears were stripped of most teeth.

At that time I bought a rebuilt 700 R4 and installed that myself, and it was fine untill this past Monday 12/8/03.

I am not sure what has happened, so if you will, please bear with me.

I had plowed where I live which is a rather large area and rough. I got stuck and rocked the truck out as is done... I heard a bang... but was able to do the work.

The next day the 8th I was asked to help plow another very long and very rugged road way into a house set way back in the woods. I got stuck there a few times but there was another truck to pull me out. I had the occasion to get my self un-stuck however more than once.. I heard 2 bangs then.. One was a broken plow stop I think as it was there and then it was gone..

A plow stop to me is the guide under a Fisher plow, which is welded on and the "A" frame runs in..

From that place it is maybe 18 miles home, and just before I got home, the engine raced up but I lost power.

This was like going from dry pavement to glass ice.. or as if the torque converter lost the bolts to the flex plates, and was scraping the flex plate for power.... No noises though..

The truck will just barely move at 4,000 rpm. I heard no noises, and there is no loss of oil.

I have a aux air cooler on the tranny which is routed from the tranny to the radiator then the air cooler.. I change as much tranny fluid as I can spring and fall like clock work.

Due to other problems I have not yet dropped the pan, and or dropped the inspection plate.

I hope either the bolts to the torque converter are gone, or the TC has failed, and that the 700 R4 has not become history...

The engine is not the original 305 now, as when it was worn out I came on a odd 350 4 bolt main with dip stick hips cast on both sides of the block with a matching oil pan, and so for kicks I have 2 engine oil dip sticks.

Finally:

My question is IF the 700 R4 is dead, I would choose to replace it this time with something else, and do not know what is best, and or what fits.

I would appreciate advise on this.

Some locals in 99' said the 700 R4 was not a good tranny, and I should have replaced it with a THM 350, while others said I should use a THM 400.

I think the THM 350 is a 3 speed tranny, and have no idea what the 400 is....

Are those options? Are there better options?

Also the transfer case is the original "New Process" I forget the number off hand.

This truck was not built to be a plow truck and has more springs for a camper, and high gears which if I recall are 2.73 to 1..

It has moved tons of snow since I have owned it and I have not been able to find lower gears... But that is another topic..

Thank you for any advise...... Mac

 

[Chuck Smith]

Well Mac, Wyldman and John DiMartino can tell you much more about the trans trouble. I will tell you what I do know.

Your transfer case is the NP208. Not a bad case. Not as strong as the cast iron models (NP 205 gear driven part time 4wd, NP203 chain driven, fulltime 4wd). Still a good case though, GM used them on models up to 10K GVWR.

The TH700R4 had problems in the earlier years, though it debuted in Chevy trucks in 1981, so I am not sure if the one you have is one of the earlier ones or not.....

2.73's are a little high for plowing, but plowing in 4wd Low should help a little.

The TH350 and the TH400 are both 3 speed transmissions. The TH400 is stronger, and also more rare.

~Chuck

 

[Alan]

Those loud bangs just might be those wonderful automatic hubs unlocking and then locking back up under power. I've seen that happen and it's so quick you don't really feel it happening. That could have some bad effects on the transmission.

And if you lost the flexplate bolts I doubt it would move at all. I had a set drop out in one of my trucks and when the last one left it was dead stop time. It made some pretty neat noises when one of the bolts would get caught between the ring gear and bell housing. Kind of the metallic equivalent of wailing and gnashing of teeth.

 

[Mac_Muz]

Thanks for the replies.. Pending weather tomorrow the trany gets a hard look see...

The orginal lasted from 87 to 99.... I bought the 84' truck in 87 so I know that history.. I can't tell if there was any tranny installed before that time.

When that tranny went it made noises, really scarey noises, BANG crunch grind, and etc etc.. The truck still moved, and I must have driven it knowing things were as bad as it gets over 100 miles and more... it was till able to go when I pulled it, and tore it down. I was astonished that it could work at all as large carrier pieces fell out once the front pump was out of the way!!!!!

This is different.. I realize that if the T converter bolts fell out, that it would feel like what I feel, and hoped to get the idea over better... I know if that occured I would hear the flex plate rubbing the T converter facing...

But I hear nothing, and get only a slight ability to move. No harsh apply when shifting from park. I have a wee bit o slop in the rear end, and can hear a gear slap normally... My U joints are fine..

The nut at the pinion gear could use a wee bit o tightening..

I think the transfer case is ok....

My hope is that the filter pick up fell off... but even then I would think the truck would move better...

My next best hope is a T conveter failure, but I have my doubts. Mac

 

[John DiMartino]

Mac, you need to pull the pan and se what your working with.If its internal you more than likely fried it already. IMO the TH700R4 is a great plowing transmission. I think its stronger than the th350 for powing and not much behind the mighty 400 for plowing. Id stick with it for plowing,but you do what you feels best.

 

[Mac_Muz]

Are there any in truck test I can do?

If the carrier is not in pieces and I know then that you do hear grinding, which I don't, what else can be wrong and tested in truck?

My Idea of testing are see to it the torque converter bolts are there (But I hear no scraping)

Some how test the front pump for pressure???

Drain and drop the pan to see what I can see.....

I was doing almost 50 mph when this happened, so I must have been in D or 3rd range.

I have no 1st, Reverse, and seemingly no 2nd and probably no OD.

I have a air cooled tranny cooler which is after the radiator cooler, and I did not smell that hot smell.

Several times I allowed the truck to rest running. The plowing was first snow and not that difficult but the snow was deep, as it was a double storm...

No excuses, just hoping a hint will get thru some how, and then someone that knows better might indicate what else might be wrong.

Like I said I must wonder if it is a bad carrier as there is no sounds of grinding.

If I had the clunk when I shifted into D at first I would think the splines were gone on the drive shaft(s) I lost a spline on the forward drive shaft long ago just after I purchased the truck.

Today is rain, but rain or no rain I must go see....

If it does turn out to be a bashed carrier I will say so.... If that is the case I would have to say the carrier is a weak part.

I work hard, but am not into abuse. A tranny should be able to hold up to getting stuck and coming out of being stuck rapidly to my way of thinking. Mac

 

[John DiMartino]

You can peform a pressure test,as long as you have a universal pressure guage.You'll need a book to do this. I think you lost a clutch/seal because it still moves a tiny bit,when you break a shaft or a planet/hard part,usually it doewsn not move at all,and the pump will pick up the schrapnel and youll hear the pump grinding and what not.

 

[Mac_Muz]

John, I could buy that diagnosis. That of a internal leak, which is what it feels like to me..

I have a Haynes Book on just THM 200 R4, 700 r4, 350, and 400's in hand. I am attempting to digest the info.

No doubt the tranny will need to come out after the initicial inspection for repairs. I would like to be able to discuss with a wee bit of knowledge with a real tech when that happens.

If I can still use this tranny I will.. If I must replace it, I am not sure what I will do... I might go with a stick shift, which I don't really want for plowing, but if a std trannies are any tougher so be it...

I know it is only a mere half ton truck, but many places I go are only so big... and a large truck can't get there well.. Thanks for the suggestion as I had not even thought of that one..

I think I might have the pressure gauge on hand.. maybe??? Mac

 

[John DiMartino]

Mac,the 700r4 is plenty tough for what your doing with it.If its built right and the Vb is good.i am running right now a 91 GMC wit hte 700r4 with over 100K on it,its towed and plowed all its life.I am pushign an 8'6" Western V plow,and carrying a 1 yard spreader,this is no light truck.ANd it gets run ahrd. the trans is original it could iuse a freshign im sure,but its workign fine.My other truck i just sold was an 89GMC2500,again with the 700r4,it had 160k when i sold it,all original i pushed commerically 3-4 yrs with it,a 7.5 fisher with wings. No troubleat all with it.All i did to both was install a med size aux cooler and service the trans evey season no matter how few miles on it.

 

[wyldman]

Welcome to the site Mac.

If you do need to pull the trans out for repairs,I'd stick with the 700R4.Good all around tranny,not to expensive to rebuild,and no swapping or modifying stuff to make another tranny fit.Sometimes the cost of adapters,and other crossmember and driveshaft mods,are more than just rebuilding what you have.

If you want to check the convertor bolts,you don't have to drop the inspection cover to do so.Just fire the truck up,and insert a piece of small wire straight up into the weep hole on the inspection cover.It will go straight up and touch the convertor.If the convertor is spinning,you will feel it.If the convertor is spinning,the convertor bolts are OK.

Just be careful,and make sure the truck is in park,brakes on,and wheels chocked.

 

[wyldman]

Forgot to mention.........I have the Factory GM service manual with all the tests\pressures and stuff for your 700R4,so if you need any info,let me know.

 

[Mac_Muz]

Does this match... My problem my work... So I type...

Haynes specs"

No park psi given all tests at 1,000 rpm brake applied.
Neutral 55 to 75 psi
Low or D2 160 to 190"
Drive 55 to 75"
Reverse 85 to 140psi

No Over Drive given

Curiously a caution is given as "Do not exceed 2 minutes running time."

Being so close to idle speed why is that? I know a higher RPM stall test heats up things fast but at this speed? Mac

 

[Mac_Muz]

Up date:

I have been able to get the truck at 2,500 rpm to back up 100+ feet, then go forward 300 feet, even up a hill apx 20 feet, again reversing into a garage where the weather is better..

I hear nothing unusual. No more testing yet, but soon the pan will be dropped..

I hope the filter sucked into itself or something in that order.

The Haynes book is not clear as to the function of the oil pump in the front housing.

I am taking a guess that this pump and anything before it might be the problem.

If I am not in error the T converter only supplies torque for power to move, while the oil pump supplies pressure for bands, and clutches. In my set up the band do not apply in 1st and reverse.

I am rather confused about now, and this was not expected at all... I need to be told how these oil pumps and T converters apply power and to what I guess.

A bit of detail would be appreciated...

I was a foreign car tech for a number of years, but I never dealt with auto trannies there... Mac

 

[ratlover]

You can get a th350 that will bolt directly into your set up but you need to have an adapter that goes between the case and the trany but it will require no mods to the shafts. You also need to make sure you have the correct spline on the output shaft. The latter 700's were better but they still aint the best trany. With a few cheap mods like a vet servo that will help OD live a and transgo shift kit with a proper rebuild the 700 will live fine. I still think a 350 is more stout even in stock form and it is very cheap to build one up. If OD isnt a real concern I would probably go with a 350 but its more dependent on your application. A 400 is the best in terms of beef but it would take a bit more to swap one in.

 

[Mac_Muz]

Well apparently the tranny is not a basket case like my first one became. It appears as a hydralic blockage to me at this time.

I can't see the reverse clutch and the 1st gear clutch which are separte acting the same way with out a common problem.

So I have changed to the idea of a repair from a switching of types of tranny's.

I am new here, and did not want to get into that my wife and I are both laid off, and seeking work, and so $$ are very tight.

I need to find the solution that makes the truck work, and as inexpensively as possible just now. Winter is on and I make a few dollars plowing. I stand to loose my accounts, and my own drive as well.. I was in panic mode, and still am but with better info.

What I need is power flow info.. I need a good diagnostic explaination so a proper fix can be made.

I just ate and will go see about a psi testing, and then drop that pan. Mac

 

[ratlover]

yes the pump circulates the fluid and applies the pressure to the bands and to everything else. You can run a trany with no TC(although its a bit tricky to stop or start )

Proper fluid level hot? If its not a pluged filter or a leaking filter/dropped filter or the like then it sounds like you nuked it bad. Correct the band aint applied in 1rst and it seems to be pissed of in every gear? so its not one band or clutch pack. Most times 700's will burn out the OD(dont ever tow or drive with a heavy load in OD with a 700. JMO and experience, a plow hanging off the front would constitute a load so dont buzz down the highway with your plow on in OD.)

Or maybe you are sucking air from your cooler? Is the fluis bubly after its been running/acting like this?

 

[ratlover]

if you are going to go about a repair your self talk to these guys at www.hptransparts.com or thier other site of www.bulkparts.com

I have the haynes and it kinda sucks in comparison to a book i bought from them that is from ATSG and thier site is listed in the book as www.atsgmiami.com and www.transonline.com.

The guys at hptrans were very helpfull to me, I assume they are still there but its been awile since i talked to em

 

[ratlover]

and according to my manual, line pressures are highly dependent on the actual modle you have.....they also show with full TV and the like....wich reminds me.....hows your TV cable and its adjustment?

 

[Mac_Muz]

Ratlover, I plow only in low range and usualy in drive there which seems low enough. This time though since the snow was deep but fairly light I was in as low as it goes...

I never plow in 4 high...

I never pull loads in OD..

This just happened with no warning at all...

Today I droppped fluid only from a drain I installed in the pan.

The fluid looked fine and I used a paint filter to catch stuff...

There was no stuff to be caught, but the fluid had a burnt smell just the same.

My luck as of late is consistant, and my floor jack refused to work.

So I spent the time going to NAPA and getting that oil and fixing the jack. With the rain and the fog things are down to a minimum slog here...

Tomorrow the pan comes down, and I will find what ever I find, and I hope I find a reason there....

I have seen far worse looking ATF before in other trannies which still worked... It was the right color, but since it sat for a few days no foaming was visable..

I am sure the system got hot. As it turns out I have no pressure gadge, so that test is out....

The TC turns the pump right? If that is so then it still could be a bad TC, but how to tell even when out I don't know......??

I have never attempted a repair on these tranny's. I was going to in 99', but when I saw the smashed case, no attempt was possible. That tranny was a total wreck.

Probably all I can attempt is minor repairs.... I can afford a new filter and the ATF to run and dump ever few days for a flush..

I was able to get the other tranny apart with out the special tools, but I saw right off those tools would be a big help re-installing parts especaily the seal protectors.

I was never this type of a tech... if this was a standard tranny I would have a far better chance as I havew done some of that along with engine overhauls.

In the late 70' and upto the mid 80's I could swap out a Volvo clutch in 45 minutes, but this stuff is a different game to me...

I suppose with a few classes things might be different.... Thanks for thew words of wisdom.... Mac

 

[Mac_Muz]

Still no idea what is wrong, but I have the idea the TC failed.

It appears the tangs on the TC fit into the pump, and so is a direct pump drive.

So if that is correct the TC is slipping, or the pump is not building pressure.

I have fond a fairly clean filter, and while the ATF looks ok, it smells burnt.There is almost no debris in the pan, and a painters filter did not catch a thing.

At this point I have no choice but to drop the tranny and send it out.. Mac