mannydantyla

I've already removed 0.006" off the deck of my '97 4.0 head, did that about two months ago to get it road worthy for an overland trip to Colorado. While there, I overheated again trying to go too fast up Monarch Pass. Was in 2nd gear going 65mph holding steady like an idiot. It cracked the heater core (I have it bypassed now), and ever since then it's been running way too hot on the highway only. We had to drive home at night when the temps where lower. Yesterday it was 100*F out and it took only 10 minutes of 70mph cruising for it to get up to 250*F. Verified with an IR temp gun. These were the same symptoms I had before I took the head off and discovered it was warped. Once I fixed it, I drove 10 hours to New Mexico and had no problems at all. Now, the overheating is back but is even worse. FML.

So can I take off another 0.006" or more and be fine??

mannydantyla

bump

97grand4.0

First thing to do before you ever rip a head off, is to check for coolant leak to see if there actually is a reason to rip the head off. That would mean get a pressure tester on the radiator and see if it leaks down. Have you done this ..ever?

mannydantyla

Did that already, there was no pressure loss but I didn't expect any.

History: the first summer after buying this jeep, it started running hot and I overheated a few times. I replaced the whole cooling system which made it a little better but didn't totally solve the issue. Then I started the testing: cooling system pressure, cylinder compression, combustion gases in the coolant (performed by a mechanic), etc. - all of them did not show positive for a head gasket leak. So I put in another new radiator, yet it still did not help my overheating on the highway issue. Then I had the oil tested by a lab, and they said I had antifreeze in the oil.

I took the head off, it was warped. I had it machined, but it back on with a new felpro head gasket, and it seemed to fix my problems because I could drive all day long with summer temps and it would not get above 205*F.

So if I have the same problem, then I don't expect the obvious signs of a blown head gasket. I expect the head to be warped and the only way to find out is to take it off.

How long do I want to continue beating my head against the same wall?

mannydantyla

Options:

- Repair the head again. If the head is warped, it will need to be machined again and I don't know how much more can be safely milled off the deck. And after one fix that failed, I don't know if I trust the engine anymore.
- Sell it the way it is and get another 4x4. It still drives around town fine
- Get a new engine
- Get a lower mileage XJ or MJ and use this old XJ as a parts vehicle
- Keep it in the back yard and turn it into a fair weather rock crawler
- part it out and sell the parts

Things that will need to be repaired sooner or later:

- heater core is cracked and has been bypassed. No AC in summer is ok, but no heat in winter is torture on long trips
- the front windshield now has a big spider-web crack in it after last weeks road trip
- the rear leaf springs are sagging and getting worse, but I can't get the shackle bolts out
- the front axle has a bad oil seal
- the front axle's passenger side u-joint was replaced but I had a ***** of a time and now the shaft is a little ****ed up
- the transmission has 255,000 miles on it so who knows how long that will last
- timing chain is probably stretched
- rear drum brakes suck but work, barely
- no AC.

Things that have been replaced/added/modded in the last 1.5 years:

- 31" tires (5 of them)
- 4-hole ev6 fuel injectors
- shocks
- front springs
- sway bar links and bushings
- steering box stiffener
- battery
- alternator
- starter
- distributor cap, rotor, spark plugs, and wires
- high flow water pump
- radiator
- fan clutch
- serpentine belt
- front brake pads
- head gasket
- hydraulic lifters
- valve job was performed on the head
- gear oil in both axles
- d30 u-joint
- upgraded to an Airaid air intake/filter
- hood vents
- DIY transfer case skid plate
- front end skid plate/stiffener from Rusty's
- lower control arm skid plates
- trailer hitch
- DIY cargo storage and sleeping platform
- DIY roof rack bars
- some door window glass

All of that adds up to well over $3,000.

I have all the receipts from the PO, and she had many many other things replaced as well: the catalytic converter, CPS, NSS, etc. but mainly had the oil replaced every 6 months and kept the thing in good working order.
Maybe the real matter is.. do I still want to do offroading stuff? Towards the end of my Colorado trip last week, I did Tincup Pass with my brother. He really didn't enjoy it at all (he HATED it and threw a fit) and he pretty much ruined the experience for me too and afterwords it just had me asking, "whats the point?"

Maybe I'll throw in a new head gasket, drive to a local offroad park, have fun, and see if I still want to do this or just have one last romp.

97grand4.0

Great. But if you say you had coolant in the oil, that means the coolant is leaking, and you should see it leaking with a pressure tester. you seem to be stuck on this concept of a warped head being the problem, not sure how that would cause a leak, however, it could be a cracked head. Again, pressure tester would show this in 3 minutes, either way. Guessing with the parts cannon can be a long expensive and frustrating experience.

mannydantyla

Alright, thanks. Also, the machinist checked closely for cracks and didn't find any

Do you know how much can be safely milled off the deck of the head?

97grand4.0

That means the machinist MAGNIFLUXED the head?

97grand4.0

[QUOTE=mannydantyla;3507622]Alright, thanks. Also, the machinist checked closely for cracks and didn't find any

Do you know how much can be safely milled off the deck of the head?[/QUOT

I'm not having any part of milling your head if you can't identify a leak, which you obviously have.
"Checking for leak in the head' means MAGNIFLUXING.

mannydantyla

I took the head off last night and the block is warped, allowing combustion to pass between cylinder to cylinder and heating up the metal in between. No leak in the cooling system. The head was still flat, however. When I took the head off the first time, I never checked the block for flatness

Yes the machinist used magnaflux to look for cracks in the head.

mannydantyla

So the deck is warped pretty bad and I can fit a .006" feeler gauge under a straight edge. That's a lot.

Now I need to decide what to do.

Options:

• get another 4.0 block
• swap in an LS or TDI engine or something
• take the block out and take it to a machine shop. But does the whole engine need to be torn down for the deck to be milled?
• put it back together the way it is and sell it or keep it around as a rock crawling trailer queen. It doesn't overheat at lower RPMs/speeds
• attempt some redneck sh*t by flattening the block myself with sand paper. I've seen people do it with small aluminum 4-cyl heads. But it's probably out of the question for larger, iron 6-cyl heads. Or is it??

97grand4.0

Ok. Overheating with no leak in the cooling system...Well that sux. Can't say I ever heard of that. Yep mill the block. Once that is in play, the whole block needs to be checked. Warped cylinder walls...mains out of line maybe...pistons burnt..who knows

PatHenry

It depends on how much money you're willing to spend. Is the body and transmission of the XJ in good shape and free of rust?

If you're not going to spend a lot of money on it, I'd call around local junkyards and see if you can find a used engine in good shape.

If you want to go all in on the thing, I'd buy a fully rebuilt and warrantied engine from a reputable source.

Personally, considering all the mods you've done and money you've put into it, I would definitely not sell it unless you can get someone to pay enough to make it worth your while. At most, I'd say try to find another XJ in good condition and use the current one for parts.

If you go the replacement engine route, whether it be for the current or another XJ, I'd store the reworked head carefully with advice from experienced forum members until you need it or can sell it for a price that will make it worth your while. Remember that that head is compatible with XJ's, Wranglers and GC's, so there's a pretty wide array of options.

mannydantyla

Also, to answer the original question, I saw somewhere that someone had taken as much as 0.020" off the head+deck. I don't know if it needs premium gas after that much has been taken off though.

HighOnLift

I'd love to see some redneck **** happen! If it's toast, I'd try the redneck fix, then if no go, use it for parts for a different jeep.

No AC and No heat is deal breaker for me... Actually no AC is deal breaker... I can wear coveralls in winter lol.....