97 XLT 4.0 SOHC - Coolant drip on passenger-side, front of engine

[ctgriffi]

Original motor in this well-maintained vehicle with a lot of miles. Noticed slight overheating occasionally over the last year or so; gauge would fluctuate up very fast and then down in a few seconds, right after getting on the road. Coolant was low, so I topped it off and the problem disappeared.

Problem is, I keep having to add coolant regularly, which indicates a leak, although I couldn't see one for a long time. Finally, today I noticed a slight coolant drip that seems to show up on the front of the engine, slightly above-and-behind the alternator.

I'm guessing this is a known issue, and I'd love to hear some likely possibilities from folks who have been down this road... thanks for the help!

 

[XLTrunner]

Only thing I know of that is behind and above the alternator is the upper radiator hose. Otherwise, I'd suspect you're the latest victim of the very common leaky thermostat housing. But, that is located more towards the driver side of the alternator rather than behind it. There are all kinds of posts on this site relating to this...and, how to go about fixing it with replacement upgrades.

 

[RustyMacintosh]

yup...plastic parts...pita to get to it without taking alt out...

 

[ctgriffi]

Okay, sounds like it's probably going to be that thermostat housing, like you guys said. I'll review some of those other threads on the subject and figure out which parts I'll need to order.

Thanks!

 

[RustyMacintosh]

Carefully, remove the hose leading to the TB. Get a long 3/8's breaker bar, release the serpentine belt. Remove the alternator.
You should be able to slip a 10mm with a small extension to get to the 3 bolts on the thermostat housing.

Replace it all, I drop the temp thermos from198 to 193. ONLY because the engines are high miles, and I find mine run better at a cooler temp.

While you are there, spin the fan clutch, does it feel like it is loose? It also might need replacing. Look at the fan, cracks?

Dropping bolts down on top of the engine and down the block is a common occurrence for me. I keep a stash of replacement bolts handy.

 

[XLTrunner]

I've found (after replacing my t-stat housing twice) that it isn't enough to just remove the alternator on my '98 SOHC. The Crank Sensor wiring harness runs snugly over the top of the housing and must be relaxed in order to lift the housing straight up to avoid breaking off any of the three plastic protruding tabs on the bottom of it and having them drop into the engine. So, in order to gain some slack in the wiring harness, you need to also remove the alternator mounting bracket to free the harness retaining clip fastened to the engine block behind it.

 

[ctgriffi]

Appreciate all the great tips, everyone.

Can anybody comment on the parts they used for this job? I'm seeing some confusing information out there and would like to know, more or less, that I've got the right stuff on hand, before I tear anything apart.

So... any recommendations, part numbers, and/or links for a 97 XLT 4.0 SOHC would be terrific!

 

[swshawaii]

Aftermarket aluminum upgrade. (Simmons, Austekk)
4.0 SOHC Metal Thermostat Housing Comparison
Thermostat upgrade help FIXED

After many reported short term failures avoid aftermarket plastic kits such as Dorman, Four Seasons, etc.

OEM upgrade:
4.0 SOHC plastic thermostat housing

 

[XLTrunner]

Whichever way you go, I would urge you to resist the temptation of the cheap Dorman and Four Seasons housings. The common upgrade list includes the following Motorcraft parts:

RH144 Lower t-stat housing
RG614 Housing outlet seal
DY1269 Gauge sensor
SW6146 ECT (engine coolant sensor)
Sensor retaining clips (Dorman 800-019)

Above parts ran me about $85 shipped from Rockauto (don't forget to use their 5% discount) a couple yrs ago.

Most people reuse their existing upper thermostat housing (part that covers the thermostat) due to the angle being correct for proper fit of the radiator hose for our pre-'01 vehicles. I know a couple people have stated they got the hose to fit on the upgraded version without any leaks...so, guess it's your call. Note that if you do use your existing one, you'll need to drive the brass sleeves out of it as the new lower housing will already have them. I believe the part number for the newer upper housing cover is RH165. Obviously, this is a good time to install a new thermostat and gasket, too. Many options on this...but, I went with the Motorcraft RT1160 on my second attempt at stopping mine from leaking (did I mention my first attempt was with a Four Seasons housing and it started leaking again after about 10 days?).

Other option being discussed on here is to go with an aftermarket aluminum housing.

You'll also want to get a new set of upper intake gaskets as you'll be removing that and you don't want to have a lean code from old gaskets. Might as well consider removing the lower intake while you're in there and replacing those gaskets as well for the same reason. Those gaskets take a set after so many years and are prone to causing a vacuum leak; especially, noticeable on a colder day at initial startup.

 

[ctgriffi]

Whichever way you go, I would urge you to resist the temptation of the cheap Dorman and Four Seasons housings. The common upgrade list includes the following Motorcraft parts:

RH144 Lower t-stat housing
RG614 Housing outlet seal
DY1269 Gauge sensor
SW6146 ECT (engine coolant sensor)
Sensor retaining clips (Dorman 800-019)

Great info, thank you! I've been scanning some of the other threads that swshawaii offered, and they're super-helpful... but also so much to read, with different problems/years/opinions involved... hard to know what to do with all that.

You'll also want to get a new set of upper intake gaskets as you'll be removing that and you don't want to have a lean code from old gaskets. Might as well consider removing the lower intake while you're in there and replacing those gaskets as well for the same reason. Those gaskets take a set after so many years and are prone to causing a vacuum leak; especially, noticeable on a colder day at initial startup.

That's the first I've heard of that! Upper intake has to be removed for this job? So, not just the throttle body?

 

[XLTrunner]

Guess you could try just removing the throttle body as I vaguely recall someone saying they could do this job that way. But, seems to me that after practicing at the JY before tackling my own repair, it still doesn't give you enough clearance to lift off or install the t-stat housing more or less straight up/down on engine. As mentioned, the reason that is important is the housing has three plastic protruding tabs on the bottom that are brittle after all these years and one or more can break off and fall into the engine opening if you try to remove the housing at an angle.

One more thing...now is the time to also replace the short hose that connects between the lower housing and the water pump.

 

[RandomNerd2000]

^Do that hose, you can NOT do it without removing the housing again, which is potentially another expensive repair if you use a plastic housing again and break the alignment tabs off the bottom.

 

[ctgriffi]

^Do that hose, you can NOT do it without removing the housing again, which is potentially another expensive repair if you use a plastic housing again and break the alignment tabs off the bottom.

Great. 10-4 on the hose replacement. I see about five options for the cooling system "bypass hose" at Rock Auto (link below); are these all basically identical? Which one to purchase?

1997 FORD EXPLORER 4.0L V6 SOHC Bypass Hose | RockAuto

 

[ctgriffi]

Actually... after reading around a bit more, it looks like the hose you guys were talking about is something else, NOT bypass hose. Hmm

 

[XLTrunner]

You're on the right track. Think I would avoid the A/C Delco and Gates that would need to be trimmed. Because they are cheap, I'd just spring for the Motorcraft and be done with it. But, Dayco, Gates and Continental are all big players in the industrial belt/hose markets...so, any of these would be fine from a quality standpoint.

 

[RandomNerd2000]

I ran a Dayco on my 2001 when the hose on there busted right before I established the head gasket was blown, it said trim to fit but it was a perfect match.

 

[ctgriffi]

Still trying to pull the trigger on a parts order, but I'm not 100% confident that the thermostat housing is the main (or only) problem. My leak is getting worse and, although I can't see the source very well, I see a lot of coolant dripping off the front of the motor... and not really any drips near the thermostat housing. I'm considering the possibility of a water pump or hose failure, possibly both, but maybe not.

I guess I'll have to tear it all down before I can really tell what's going on there, and then start ordering parts.

Which means no driving for a good while, dangit.

 

[RandomNerd2000]

Hose or thermostat housing is my bet, when my bypass hose failed, it made one heck of a nice belt squeal, and a HUGE puddle, like size of the hood.

 

[2TimingTom]

I've got a similar issue.

'97 SOHC with about 155k miles.

I've got a leak only when running. It drips down mostly the passenger side and blows all over the axle and steering (SAS stuff.....). Being that it only leaked when running, I replaced the water pump- thinking that it was the weep hole leaking. The old water pump had a little bit of play in the shaft and the gap between the impeller and the housing was noticeably larger on the old pump, so it was a good move to replace it anyway.

Also replaced the 2 sensors on top of the thermostat housing and the thermostat itself.

Started it up and it seemed to be good. Once the temp warmed up, it started leaking a little- just like it was leaking before. I can't pinpoint a source, but I can barely see that it's wet on top of the engine between the V.

Does this sound like the thermostat housing leak?

 

[donalds]

I've got a similar issue.

'97 SOHC with about 155k miles.

I've got a leak only when running. It drips down mostly the passenger side and blows all over the axle and steering (SAS stuff.....). Being that it only leaked when running, I replaced the water pump- thinking that it was the weep hole leaking. The old water pump had a little bit of play in the shaft and the gap between the impeller and the housing was noticeably larger on the old pump, so it was a good move to replace it anyway.

Also replaced the 2 sensors on top of the thermostat housing and the thermostat itself.

Started it up and it seemed to be good. Once the temp warmed up, it started leaking a little- just like it was leaking before. I can't pinpoint a source, but I can barely see that it's wet on top of the engine between the V.

Does this sound like the thermostat housing leak?

Yes sir