Will new valve job overstress old bottom end? | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

Will new valve job overstress old bottom end?

jammor

Member
Joined
March 20, 2015
Messages
32
Reaction score
15
Location
Atanta GA (Conyers)
City, State
Conyers ga
Year, Model & Trim Level
1996 explorer XLT
96 XLT OHV V6 4.0L 250K on original motor

Problem: Blown head gasket (and/or cracked head)
Question: Should I include a valve job when having the heads replaced or will having a super tight top end overly stress my lower end and cause it to fail, or fail quicker?

Condition of rings: Good compression on all cylinders. Professional mechanic did this and a leak down and said there is no more than 7% variance among cylinders. No coolant apparent in the oil, or coolant for that matter and lots of white sweet-smelling smoke from tailpipe. I've recently done radiator, H2o pump, therm, alternator, rear main oil seal, oil pan gasket- lots of sweat equity on my part and add new tires I also have a bit of financial investment here.

Mechanic recommended just doing the heads and gaskets, inspect tappets, push rods, etc. And mechanic recommends just having the machine shop pressure test heads for cracks, clean and plane them (shop cost $80 per head)- no valve job. I can get all that done for $1,050, includes all parts, plugs, coolant, oil, machine shop etc.
Or I can buy new cylinder heads (Kingscylinderheads.com , $294 each) which come assembled with new valves.
Finally, if one head is cracked and needs to be replaced, wouldn't I be buying a new head anyway- thus one side is gonna have a nice valve job and one wouldn't.
Total cost goes from $1,050 to $1500.
And yes, I do love the truck or I would be looking for a cliff to roll it off of. I plan to keep driving it, even if it becomes a secondary driver.
Finally- there's the newly rebuilt engine from Advance- and I could put that in myself- though I'm about tired of DIY on this car- and I'd have to get a quote.
Thanks in advance for anyone's insight, comments, leers, jeers- I can take it- seriously if you think I'm throwing good money after bad please advise- I won't take it personally. Glad to have the forum
 



Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!
.





i'd just pull the heads have them pressure tested check surface of block and heads if they are all good reassemble use good head gaskets.
roscoe
 












If it’s just a head gasket then I would leave the top end alone. If you have to replace a head doesn’t a valve job come with a new head (depending on how you buy it?)

About to to my 150s 302 with the same head or hopefully head gasket problem. Mine has 305k and no way would I tighten top and not the bottom.
 






pressure test might not show the cracks in the heads.
While they are off, take a magnifying glass and look carefully at the area where the intake and exhaust valves are closest together. This is the problem spot on the 4.0ohv heads.
 






if you pressure test them if they are cracked it will show bubbles. worked at machine shop for 5 yrs pressure test will show problems down deep where you can't see or magnaflux isn't visible.


roscoe
 






Um, ok.
Mine didn't. Maybe the machine shop that did mine didn't do the job properly.
I was trying to help the op so he would know where to look.
I guess its completely up to him on what he wishes, or doesn't wish to do.

To the op, there are pictures here on the site of where the heads crack. I will have some, and so will JD4242.
 






I don't know if reusing these heads at that age and mileage is a good idea. They have a tendency to crack. This is what the NAPA machine shop told me. They do not service them because they had comebacks.

There is a guy on ebay selling them for under $400 for a loaded set, he has great feedback. The $80 job does not include any valves or springs.
Do you have misfires?

I had something similar, I know this isn't for everyone, but a bottle of k-seal solved all my issues. I have zero misfires in cyl 4 now for 1000s of miles, I used to have over 5000 on each trip, sometimes blinking CELs. It never rode better. K-seal does not clog anything if your coolant is clean. My truck does have some rust, and I know it won't last forever, so I took this route. I know you can love these trucks but they are getting to the point of scrap value worth.

But from what I understand this could be a long term solution, and you can always repair it.
 






Here's some pic's of the ohv cracked heads.
scroll down in the thread a bit.
4.0 ohv cracked head pictures anyone??
As mentioned, if your looking for cracks, magnafluxing might help in the search also. A few minutes with a magnifying glass might save you some money though.
 






Thanks Dono and Roscoe: Took the truck to mechanic Monday with instructions to pull and inspect heads (pressure test)- if OK they will not do valve job. If either head is cracked then I'll probably go with new heads from Kingscylinderheads.
OR
Say I have valve issues requiring one side to get rebuilt then I'll have both heads rebuilt- guessing doing that to both heads would be cheaper than the $600 total for two new Kings (I still think that's a steal at $294 per head plus $30 covers shipping for both).
No, I don't work for Kings- just read about them hear.
96eb96: I threw only one misfire code during this whole 3-6 month mystery of "Duh where is my coolant going???" It was P0304- I pulled that number 4 plug and had 155lbs compression......didn't know what to do then so I took it to my professional. I would have done a "blue devil" head sealant temp fix but the whole cooling system is new and the heater core works--just too much of risk there I'd set myself even farther back...

I guess in the end here its really a crap shoot. I am trying to spend $1,000 and drive 2 more years. I know I can spend $3,000 and drive 5 (including cost to have a pro switch engine out). But I am hedging my bet against the fact the transmission will probably then immediately fail!!! Oh did I say that out loud!?!?


Thanks for all your replies and I will post updates here going forward.
 






Back
Top