New member here, so bear with me on my short commings.

Heres some details.
The engine is in a 88 model 36' motorhome on a John Deere chassis, has C6 Ford trans. Rear end, I'm not sure, but papers listing parts say it is either a 4.53 or 4.68 gear. Which one I dont know, but at 65 mph the engines turning around 4800 rpm
Engine is the 385 series 460 built in 1987. Heads are E6TE-DA castings.
My problem is exhaust valves beating up into the heads.

First problem, was trying to get a skip out after our first trip, plugs, wires, cap, rotor button did not help or stop the skip. Skip wasnt that bad going down the road, engine just didnt have the power I thought it should & you could hear it good at idle.
Next trip out, broke down comming home, with one broke push rod & two bent + three lifters jumped out of their holes.
Didnt know it at the time, but even with those lifters pushed out it still had about 10 psi of oil presure.

Getting home, or I should say limping home, pulled the valve covers & # 7 cylinder the exhaust rocker arm was sticking way up & loosing the bolt you could see the valve closing.
After finding that we just went ahead & started pulling the heads off.
Every exhaust valve in both heads was beat up into the head casting & it looked like there were no seats in the heads to begin with, just the seat machined into the casting.
# 7 exhaust valve was beat so far up in the head it had to be replaced.

???? Would Ford have done that in 1987, no seats, just the seat machined into the casting & knowing leaded fuel could ne longer be found at a station.

Now thats out of the way.
Completing the head repairs, machine shop said heat was the problem & that stellite seats would need to be installed to cure the problem.
The one head I still had we could use, thats what was done along with seating the valves & all guides checked with in spec, good to go.
Replacement head, it was suppose to have the stellite seats already in place.

So now I'm thinking, thats out of the way & we can enjoy traveling again, except after 3000 miles the heads are off again with the same problem.

After taking the heads back to the machine shop & doing a bunch of checking myself, come to find out the wrong seats had been installed in the one head we could use & the replacement head who knows.
Little trick I was told to check by, stellite seats, a magnet wont stick to them & it wont. Old messed up seats the magnet did stick, wrong seats in both heads.

Now, after the second time repairing the heads, from the same shop, ended up costing us $225.00 for the same job they were suppose to do right the first time.
Got the heads back, I pulled the exhaust valves out myself last night & the seats are non magnetic just like a stellite suppose to be.

The supplier of the seats being used is a company called SBI & they are telling the machine shop that because of the heat involved the stellite seats are becomming magnetic, which I think is bull & just back peddling on their part.
Crazy part, all this time dealing with the heads & seats, ol valves look almost good as new or close. Seat on the valve is flat & edges are sharp no roundedness to them at all, figure that out. Magnet wont stick to the valves, so stainless or stellite maybe.

I'm not the sharpest kid on the block, not the dumbest either & I've had my hands in oil working on engines for many years, all different kinds & what I've had my hands on no body can fool me on.
We've had this motorhome less than 2 years & spent around $3500.00 in engine related repairs.
Get this now, the previous owner said the engine had never been touched except for an air pump replacement, well, Ford Motor Company must be mighty messed up to put two different brands of head gaskets + the heads didnt match, intake gaskets were the grafoil type with blue silicone all over them & the gasket under the EGR valve was home made.
Previous owner lied & only thing, it was at least 8 months before we realy found out what the problem was & more than likely dont have a leg to stand on.

Thanks for just looking.
Neil

 

first thing I would note you mentioned different gaskets from ford my bet is no someone has been into that engine before and did a valve job that is why the exhaust seats went away. from the factory they are induction hardened not actually hardened seats installed.
Next if the shop lied to you about installing hardened seats I wouldn't have paid them a thing to fix what they didn't do the first time, second off I would find a new shop.
Next if your turning 4300rpms at cruise speed your turning that motor WAY to hard that is getting close to max rpm at cruise, the motor should be turning no more then 3000rpm at 65mph so check out why it has those gears and what else has been changed and get it changed back.

you asked about Ford just grinding the seats into the head and was that right? yes but they did what is called induction hardening (heat treated and quenched) this is very common but it only hardens a fairly thin layer so if you do a valve job on it you grind the hardened section out and you have just soft iron after that and need to install hardened seats to prevent the problem you have.

 

Neil,
I have to say I think monsterbaby is right.
There's something else wrong.

These engines are darn near bullet proof.
Tens of thousands of school buses, Highway Department and other fleet vehicles attest to that fact.

Can you feel it shifting into top gear?
Could that "skip" you heard at first have been just an exhaust manifold leak, or a ticking lifter?

You state 4800 rpm @ 65mph.
As this is a motorhome, I imagine most of the time it is on the highway.
Hours on end at such high rpm's has got to pump a heck of a lot of heat into the exhaust valves, seats, guides, manifolds etc....
Perhaps enough to anneal the valves and/or seats.

Seems crazy that three lifters could jump their bores, or pushrods would bend, at any sane engine speed.
If you saw the valve closing as you loosened the #7 rocker arm then I would think it was not a stuck valve that bent the pushrod in the first place, unless it had got so incredibly hot as to have bound up in the guide.

"Never been touched"?
Was there any evidence of the timing chain ever having been replaced?
That could well explain the lack of performance.
How many miles are on it?

Sadly, you could have had the whole engine replaced with a re-man longblock for that $3,500 and still had a lot of gas money left over.
(or enough for a new R&P setup)

 

Thanks for the replys.

A member from RV.Net sent me over here, saying if I was fortunate enough maybe monster baby would chime in, looks like I'm very fortunate then for you to be the first one.

Sorry about the long post, didnt realize it was that long till I submitted & read it.

Heres some more details.
We use the M/H traveling to ATV races & pull a 24' enclosed trailer. Best I can remember, I think odometer has 70,000 now & I have racked my brain trying to remember what it was when we bought it, but more I check into things, wouldnt dought it has tripped.

What your saying about the induction hard seats, that makes since now, because you could see there was no machining around the valve edges like it is on a head thats had seats installed & only the sunk in hole where the valves beat in.
I guess big OEMs got to cut corners somewhere.

Far as the timming chain, didnt look like any part on front of the engine had ever been removed & thank the lord, he helped me get those long bolts out. Those long ones had a orange silicone on the threads,,, that normal from Ford.

Problem with the shop I used, owner, we've been friends for years & have an account there. I just found out the other day when I picked the heads up they are closing up shop after Dec, wish I had known that a good while back, so that kind of explains the whole deal.
If the previous owner of the M/H hadnt lied to us about the engine just to get it sold, we may have backed out buying it or either he could have sold it to us at a to be repaired price. He got his money though & we learned a lesson, but you know every dog has their day.

Got another Q, replacement cam I got bought, has 280 intake & 294 lobe lift & if I'm reading right, non adjust 460 rockers are 1.73 which would be around 4.84 intake & 5.09 lift on the exhaust. This engine has the deep oval dish pistons with a valve releaf on each side, will the 5.09 exhaust clear the piston top at TDC,,,oh & the timming set, the crank gear I set @4* advance, do I need to set it back to straight up TDC or @ advance will the valves hit.
Thanks for the replys, Neil

 

ok several things you mentioned tell me someone has been in that engine. first no you won't find orange silicon directly from Ford. next you won't find an adjustable timing set directly from Ford so it's a replacement timing chain. So I would almost bet someone has at least done a valve job at some point on that engine which took the hardening away from the seats.

Your question about the cam lift is yes it will clear, a .500 lift cam shouldn't be anywhere near enough to have piston to valve clearance issues it's only about .015 over stock lift specs.

Also Jim brings up another point are you sure it's getting into top gear? when I put it in a gear calculator 31" tire (265/75/16 is pretty close and a common motor home tire) with a 4.56:1 gear, in second gear at 65 mph is 4690rpms and that is close to what your saying so I am guess your trans may need some work too.

 

I'm not 100% sure, but the timming set looked stock that I took out. Was only one key slot in the crank gear & you could look at the pointer & the tooth was a bit counter clockwise of the key slot.
I have installed a new set ( Edelbrock ) & the crank gear has three key slots & have it set @ 4* advance right now, but no covers have been put back so would be easy to change if needed.

On the trans, I think its changing, C6 has three gears, right. Man it would be nice if it had 4 gears, that would get those Rs down as well as noise.
Tires are 19.5 & cant remember the Dia.

Say, if I jack up one rear side, mark a line on tire & drive shaft & rotate the wheel, how do I figure the ratio.
The papers in the M/H say it is a Dana rear with either 4.53 or 4.68 gear, but I realy dont know. Been thinking if I could put in a 2 speed truck rear end in it or either a standard trans turned around backwards at the tail shaft to make overdrive. Only thing, has a locking brake at the tailshaft of the trans, no parking paul in trans.
Thanks, Neil

 

well that gear ratio and the rpms your saying your seeing would be almost 100mph with a 32" tire and a common tire size in that rim diameter would be 245/70r19.5 which would be just a hair over 32" so something is definitely off there somewhere.
doing the math, 4800 rpm with a 1:1 transmission (C6 in high gear is 1:1) and that size tire would require a 7.00:1 gear

 

to figure ratio that way jake up BOTH tires, turn both one full revolution and count the turns of the driveshaft. The ratio's you gave will be approx 4-1/2 turns.