Ford 4.6L Gurus - Intake / Thermostat Advice

[tony1679]

Please read carefully. Not the typical problem here:

My sister just bought this 2003 Mercury Grand Marquis. No prior coolant leak. This DOES have the aluminum crossover on the intake. It had symptoms of a bad thermostat, along with heater issues (seems to be the same problem). I replaced the thermostat without issue. The old seal was definitely bad. I carefully replace the two bolts (knowing the common issues). I come back 5 minutes later and coolant is pooling under the car. After several hours of investigating, it is NOT coming from above the thermostat. I absolutely positively did not overtighten the bolts (for this very reason). I am 99% convinced I did not crack the intake, and I am a pessimist.

I later find that the gasket between the aluminum 'housing' (that the thermostat rests inside of, not the piece above that attaches to the hose), and the plastic intake manifold below it is bad. I can see the rubber gasket sticking out into the housing with the thermostat removed. I tried to force it back into place, but no luck. It is not torn, deteriorated, or broken. It just seems to have popped out of place.

What are my options? I'm trying to avoid removing the intake. Thanks in advance!

 

[Colt45ws]

Unfortunately, you are going to have to pull the intake and put on a new set of gaskets.

 

[MikeHigg]

Yep, pull the intake, make sure there are no cracks in it too, they are often at the rear. If this is the original intake I would also consider just replacing it with this age (but that's just me, I replace suspect stuff because the labor is the big cost, although an intake is pricey, I know cause I recently bought one).

 

[ford46guy]

Even the new aluminum crossover intakes can fail. The base is still made of plastic and can warp or have issues. The gasket can fail as well, they are formed O-rings on a rigid base.


I would say 99% pull it but if you want to mess with RTV may be a temporary fix (not suggested). Inspect the gaskets and sealing surfaces and go from there.

 

[tony1679]

Ok, new info. There is a separate gasket (as I thought) between the thermostat housing and the intake. I have found out for sure that I can get a replacement (O'Reilly/Autozone part #35958). So now the only question is can I separate the aluminum crossover from the rest of the manifold? It appears there are 3 bolts on the underside of the crossover on both sides. Are these what hold the crossover in place?

 

[bdcardinal]

Yes those are the bolts, but they come up from the bottom so you have to take the intake off to access them.

 

[tony1679]

Originally Posted By: bdcardinal
Yes those are the bolts, but they come up from the bottom so you have to take the intake off to access them.
After removing the belt, alternator, and air box assembly/tube, I have pretty easy access. I'm going to try removing them without removing the whole intake. If that allows me to separate the crossover from the intake, problem solved. Yes, they look hard to get to (at least 2 of the 6), but I am looking at this intake thinking removing it will be a whole lot harder....

 

[bdcardinal]

Intake on a Grand Marquis is cake. Under an hour and it is off. Whenever I took those intakes off, I would take the upper portion apart and clean out all the passageways.

 

[ford46guy]

Rear bracket can be a PITA.

 

[tony1679]

Update: Major problem. Seeking advice.

Here is the old thermostat seal, definitely shot. The thermostat that came out was a Motorad, not a Motorcraft. Which means someone was in there before...

Once the thermostat was removed, I found this. It is the gasket bulging out from where it should in the rectangular hole.

The crossover was able to swivel after removing five of the bolts. The sixth (farthest to the passenger side couldn't come off, the head was in the way).

Once I got in here, what I found really [censored] me off:

First of all, the groove the gasket fits into is broken in two places.

Here is why I was/am [censored]. This is what I found beneath the crossover, and I know [censored] good and well it didn't come from Ford:

Why yes, you probably guessed right, that IS a rubber band and electrical tape.

So, again, what would you do? Try to repair this groove so that the gasket seals correctly, or replace the intake? I know the correct answer is to replace it, but my family will probably have me try to fix it. So I guess the other question is, if someone put a gun to your head and said to fix it, how would you do it?

And yes, I know there is some coolant in the spark plug hole, easy fix...

Many thanks in advance.

 

[Colt45ws]

If I had to fix it to get home, I would put the gasket back in the lip as best I could and dump a gallon of RTV around it.

 

[Trav]

Some things just shouldn't be fixed and this is one of them. At some point the mickey mouse repair will fail and might take the engine out with it if someone doesn't notice it overheating.
Guess who is on the hook. Replace only or don't do it, its better to be called and A hole for not doing it rather than get the call saying the thing is on the side of the road with coolant coming out all over, and its your fault for fudging the job.

 

[The_Eric]

Originally Posted By: Trav
Some things just shouldn't be fixed and this is one of them. At some point the mickey mouse repair will fail and might take the engine out with it if someone doesn't notice it overheating.
Guess who is on the hook. Replace only or don't do it, its better to be called and A hole for not doing it rather than get the call saying the thing is on the side of the road with coolant coming out all over, and its your fault for fudging the job.


I agree.

Suck it up and fix it the correct way.

 

[TFB1]

Originally Posted By: Trav
Some things just shouldn't be fixed and this is one of them. At some point the mickey mouse repair will fail and might take the engine out with it if someone doesn't notice it overheating.
Guess who is on the hook. Replace only or don't do it, its better to be called and A hole for not doing it rather than get the call saying the thing is on the side of the road with coolant coming out all over, and its your fault for fudging the job.

The 4.6 Fords from 1998 have a fail-safe system to alternately shut down cylinders if overheating(that sensor threads directly into head)... I know it works as the wife ran ours out out of coolant when it's intake split at the ECM temp sender bung... Like most women, she didn't have a clue it had a issue till it started running like po-po... The CEL came on and when I scanned it, had P1299 code that is set when cylinder shutdown is activated...

 

[Trav]

N* engines had it also, they still sustained top end damage. I wouldn't use that system as insurance to put off a needed repair or doing a bad repair, its not worth it.

 

[bdcardinal]

Replace the intake, it is really not that hard of a job to do. The hardest part is the goofy bracket that is bolted to the backside of the engine.

 

[ford46guy]

I should put of pic of what my MGM had when I got it. Someone used JB weld around the cracked tstat housing. They also removed the stat and it had a code. Leaking into cyl 5 and causing misfire headaches.

 

[tony1679]

Update - I was able to convince my family to replace the intake. Will be replacing with a Dorman. After about 4.5 hours (taking my time and labeling everything) it's out! Removing the bolt/bracket against the firewall was a breeze (and I have large hands). Although getting it back in may be more difficult...

I will be cleaning the throttle body thoroughly while it's out. I did find some of the valves to be pretty dirty, and the chambers between the intake and valves all had a wall of black gunk approximately 1/8"-1/4" thick (sludge?). The engine itself is not sludged though. Should I wipe off these chambers or leave them, considering the valves/piston tops are exposed? Anything else I should do while I'm in this deep? New intake will be installed late tonight. Thanks in advance.

 

[TFB1]

Originally Posted By: tony1679
Update - I was able to convince my family to replace the intake. Will be replacing with a Dorman. After about 4.5 hours (taking my time and labeling everything) it's out! Removing the bolt/bracket against the firewall was a breeze (and I have large hands). Although getting it back in may be more difficult...

I will be cleaning the throttle body thoroughly while it's out. I did find some of the valves to be pretty dirty, and the chambers between the intake and valves all had a wall of black gunk approximately 1/8"-1/4" thick (sludge?). The engine itself is not sludged though. Should I wipe off these chambers or leave them, considering the valves/piston tops are exposed? Anything else I should do while I'm in this deep? New intake will be installed late tonight. Thanks in advance.


It's due to weeping valve stem seals, oil vaporizes and leaves deposits, clean it up and start using high mileage oil... M1 HM has cut consumption in half on my '98 that a couple seals were showing some leakage(noted last year when intake was replaced)...

 

[HM12460]

The last 4.6 intake I had to replace came from Summit Racing Equipment. At the time they had an all aluminum intake so I bought it, installed. Appeared to be a quality piece. Not real confident of that Dorman manifold at all.