98' 4.0L SOHC Head Gaskets?

[jharvey74]

I have a 98' Explorer XLT 4.0L SOHC. I have to admit that this truck has always run so well and been so reliable that it kind of caught me asleep at the wheel. It was very slowly losing antifreeze and because I wasn't keeping an eye on it (6 months since I last flushed the system), I didn't notice until it started running hot the other day. So I check it out, and lo and behold it's quite low on antifreeze. I re-fill the fluid and it's still trying to run hot. I replace the thermostat and gasket and the over-heating goes away completely. The truck is running great again, except it's still very slowly losing anti-freeze. There are no external leaks. So I take it to the shop to have them pressure test it and dye test it. Nothing shows on the pressure test, but the dye test just slightly registers that there is some exhaust gases mixed in. So, that's where I'm at now. I'm considering pulling the heads and replacing all the gaskets OR wondering if I should just leave it be for now (it's running perfect again) OR if it might be a different gasket that would be easier to replace. It's only been a few days, so I haven't had time to accurately gauge how much coolant it's losing (thankfully it's that slow).

I know the SOHC is a particular challenge as compared to the OHV (the timing chains come to mind), but I'm wondering exactly how much more difficult this will be? I've done head gaskets before, the most recent being a 92' Plymouth Sundance 2.2L I4 and a 96' Chevy Lumina Sedan (2.4L I4 if I remember correctly). The Plymouth was a slight pain only because I had to replace the head, so I had to reset the engine to TDC P1. The Lumina was as simple as pulling the head, replacing the gasket, and remounting the head.

So my questions are:

Should I be able to replace the head gaskets without having to pull the engine or will I not be able to access the rear timing chain?

Do I need the "special" locking tools for the timing or can it be done manually?

Is there anything else I should be considering that might be unique to this job for this engine?

Thanks in Advance for any and all help,

Jim

Edit: I should add, there is no evidence of oil/coolant mixture as of yet. I drained the oil (needed to be changed since it had been running hot anyways) and it looked fine. Also no visible oil in the radiator or overflow chamber.

 

[rmcknight]

easy, yes you can pull both heads off with the engine in the car. It will be a big job though, as the front timing cover and all the stuff on the upper upper engine need to come off first.
and yes, you will need the timing tools to re-set the timing properly.
However, you will NOT be able to replace the chain / sprocket at the rear of the engine without pulling the engine (or trans).
I would not recommend you do this if all you have is a slight water leak. It may not be the head gaskets anyway.
If you do go ahead with the job, check out my step by step guide (with photos) on how to do it right (as link below)
http://docs.google.com/Doc?id=dhq242v8_4hm6cgp

 

[jharvey74]

Thanks for the link, I'll check it out for sure. I know I'm getting exhaust gases in the coolant, so one of the seals is bad. Do you recommend some other, more easily accessible things I could check/replace first? There are no visible, external leaks, even under pressure. I would rather not yank the heads if it can be avoided, since the truck is still running great. I'll have a better idea how big the problem is in a week or so, when I've had time to measure how much coolant I'm losing. Wherever the leak is, it's pretty dam small. I thought about trying a sealant, but I tend to shy-away from those, for fear of clogging the system somewhere else. As it is now, I could probably leave it and just watch my coolant level, but we also use the truck to tow our tent-trailer when we go camping. It's a light trailer, but I'm worried about putting any additional stress on the truck or driving it a prolonged distance without knowing why I'm losing coolant.

 

[rmcknight]

Are there any bubbles in the radiator (once warm/hot) at about 2000 - 3000 rpm.
Dont get a steam burn, open when cold and then get up to hot temp.
If not, then look for small leaks arround the seam of the radiator and dripping down under the front onto the road, this may only happen when the car is cold and just building up to hot (as the rubber seals are still cold, but there is pressure in the rad).
This is a known issue with "tank" based radiators.

 

[jharvey74]

Are there any bubbles in the radiator (once warm/hot) at about 2000 - 3000 rpm.
Dont get a steam burn, open when cold and then get up to hot temp.
If not, then look for small leaks arround the seam of the radiator and dripping down under the front onto the road, this may only happen when the car is cold and just building up to hot (as the rubber seals are still cold, but there is pressure in the rad).
This is a known issue with "tank" based radiators.

I found one small leak was the radiator cap. Replaced with a new one and that leak stopped. I also noticed a small dripping on the passenger side. When I inspected underneath, it appeared as if the leak was actually from the driver-side, but was dripping into a plastic "shroud" underneath and then dripping out from the shroud on the passenger-side. The only thing I found that appeared to be leaking was the lower radiator hose, right where it connects to the radiator, but upon closer inspection, it looks like the leak from the radiator cap was dripping straight down to the lower hose (which I hadn't wiped off previously when I changed the cap. So, I'll check the hose again tonight (after I wiped it clean yesterday) and see if it actually has a leak there. I also have to start-over on gaging how much coolant i'm actually burning off through the gasket, since previously it could have been leaking from the cap.

Just in case I end up having to replace the head gaskets, where do I find the cam locking tools?

 

[nightmania]

I have a 97 explorer I picked up for $275.00. The mechanic I picked it up from said it needed head gaskets (why I got it so cheap ). My question is this, I have removed almost everything possible for the left side head gasket minus 2 8mm external torx bolts. I can not seem to find any automotive place that has the socket size I need. Should I just put it back together and try the K&W Permanent Metallic Block Seal or Thermagasket to see if they will solve the problem. I am only looking for a 6 month fix as I am intending to drop in a new engine/transmission to make it like new.

The shop wants $1600 to do the heads, which I can't afford at this time and I need the truck to be able to make a 3500 mile trip soon.

If anyone has tried these with success, please any help is appreciated.

 

[Gloff]

Are there any bubbles in the radiator (once warm/hot) at about 2000 - 3000 rpm.
Dont get a steam burn, open when cold and then get up to hot temp.
If not, then look for small leaks arround the seam of the radiator and dripping down under the front onto the road, this may only happen when the car is cold and just building up to hot (as the rubber seals are still cold, but there is pressure in the rad).
This is a known issue with "tank" based radiators.

I would have to agree, on my 99' SOHC, the guy at the shop noted that the seams where the crimps to the tanks can get loose and create a small leak that goes away with full pressurization. Be on the lookout though, I overheated when it was low for about 10 seconds, and now I have a blown head gasket.