4.0 pushrod coolant leak | Ford Explorer Forums - Serious Explorations

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4.0 pushrod coolant leak

ND Ford

New Member
Joined
June 24, 2019
Messages
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Location
Argusville, North Dakota
City, State
Argusville, North Dakota
Year, Model & Trim Level
2000 Explorer Limited
Callsign
KB0BRY
Have done some reading about the 4.0 pushrod engine leaking coolant here and there. I have that problem with the 4.0 in my 98 Ranger. Coolant disappearing, oil was milky plus white exhaust at initial startup/warm up. So I removed the plenum, lower intake, front engine cover and found several places where the coolant was getting into the engine oil. Reassembled with new Felpro gaskets. No more coolant in the oil. BUT....I still had coolant disappearing, white exhaust on start up/warm up. So I parked the truck and next day when the engine was cooled down, pulled all the plugs and looked for any signs of coolant on them, None found. Used a bore scope, looked at each cylinder, nothing unusual, no coolant in any cylinders. All the plugs looked nice and clean. So I rented a coolant tester, the kind what detects exhaust in the coolant. Did that test on two separate occasions, no exhaust in the coolant either time. Then I did a coolant system pressure test at 15 pounds and started finding some slow leaks on hose connections, lower radiator core...so quit that before I blew out the radiator. Never find any coolant on the floor under the truck so gave up on the coolant pressure test. Still loosing coolant and white exhaust on start up/warm up. Disappears after the engine is warmed up. I had done a compression test earlier with inconclusive results but decided to do a cylinder leak down test. Pulled all the plugs, tested each cylinder at top dead center with 80 pounds of air. Watched for bubbles in the radiator. Every cylinder tested 80/80! So no blown head gasket or combustion chamber problem which explains why all the spark plugs looked good and no coolant in the cylinders. So...now I am thinking possibly a crack in a cylinder head between the intake manifold and intake valve somewhere and am planning on pulling the plenum and pressurizing each intake passage. Any ideas or does anyone see anything I might be missing here?
 



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@ND Ford

Welcome to the forum!

Your first post write-up is one of the most complete & understandable write up's I've read on this forum regarding systematically hunting down coolant loss on an OHV for quite some time.

Keep on following the path that the "mechanic voice" inside is guiding you down. As I see/understand it, after your plenum pressure test you're pretty close to ultimately pulling the upper/lower intake and seeing what's up, and if necessary, pulling the heads...

Sometimes ,despite all the advanced testing methods & tools/gauges/scopes, some symptoms only show up under actual driving conditions OR complete tear down & inspection...

Good luck, keep us informed, pics would be great!
 






Thanks for the quick reply! Looking at these forums and some of the expertise, I find a lot for me to learn here. Just takes time to read it all and digest what others are doing with their Fords. I have GM, Chrysler along with several Fords and I like the Fords the best! I will keep reading and maybe I can even help on some of the technical issues. Engines are my favorite but also have some talent tracking down electrical problems. Been repairing engines since I was 9 years old and never seem to get tired of it. Thanks again for the support. I take lots of photos but not certain whether my membership level will allow me to post them.
 






I take lots of photos but not certain whether my membership level will allow me to post them.

Store your pictures on Imgur for FREE & then link to them using HTML code for forums.

Link: Imgur: The magic of the Internet

Was also thinking, the other main engine component that has coolant passing through it, and a thin paper gasket separating coolant from the engine oil, is the Timing Cover. BUT, normally you will see coolant weeping from the outside of the timing cover FIRST, before the gasket fails and lets coolant into the engine. In fact, there is a special "weep channel" built into the timing cover that coolant should come out of. letting you know early on there is a problem.

Here's two links with some good pics about what I'm talking about.

Link 1: Removing timing cover on 4.0 OHV

LINK 2: 4.0 OHV Timing Cover & Gasket Issues
 






A follow up....while I had the upper plenum and intake manifold removed. I contemplated pulling both cylinder heads and having them magnafluxed. Since I couldn't detect coolant in any of the cylinders and all the plugs looked normal/clean, I decided to refrain from pulling the heads, reassemble the motor and see if there was any improvement in the coolant loss issue. I did improve some by keeping the oil clean....but still have coolant loss, more than just a few ounces every warm up/cool down cycle. So....the battle continues!
 






Imgur?? Not sure about that one Dave. I will check on that. Thanks. Would be great to post a few photos that might help others also.
 






I used to use Photobucket, until a few years ago they turned into a pay to play site = $399 a year...

Imgur is where "everybody" moved over to for $.0.00

Link: Imgur: The magic of the Internet

NOTE: If you use Chrome, and can't view Photobucket photos on this and other forums, there is a free APP that Chrome offers that "fixes" things and allows you to see forum pics that were hosted on Photobucket. You'll see a "third party hosted" error message until you initiate the hotlink "fix".

Chrome Photobucket Hotlink Fix: Photobucket Hotlink Fix
 






Was also thinking, the other main engine component that has coolant passing through it, and a thin paper gasket separating coolant from the engine oil, is the Timing Cover

Yep Dave.....That was a problem on my engine. That was my primary reason for pulling the front engine cover/timing gear cover. Those two coolant passages, one on each side were seeping some coolant onto the outside of the engine. Some of that coolant was running down into the oil pan at the lower end of that front engine cover. Once I cleaned that all up put it back together, my oil stays clean now.
I am wondering however, and maybe you have heard of it, on the intake manifold, the aluminum part, not the plenum, there is a coolant passage through it and I am wondering if anyone has had any experience with lower intake manifolds developing an internal crack, leaking coolant into the engine through the intake passages. So basically the engine would be sucking a small amount of coolant into possibly one cylinder while the engine is running.
I have not started on it....but am planning on pulling the plenum which will expose each individual intake opening. I can fabricate a square steel plate which can be secured to the intake manifold using the existing plenum studs. I will drill and tap a quarter inch NPT hole in the plate and thread in a fitting to attach my air hose/gauge. Hopefully locate a crack somewhere between there and the intake valve on one of the cylinders. If not.....back to the drawing board!
 






I am wondering however, and maybe you have heard of it, on the intake manifold, the aluminum part, not the plenum, there is a coolant passage through it and I am wondering if anyone has had any experience with lower intake manifolds developing an internal crack, leaking coolant into the engine through the intake passages. So basically the engine would be sucking a small amount of coolant into possibly one cylinder while the engine is running.

I've heard of it, understand completely what you're thinking, BUT I've never seen a write up on it in my 14 years in this forum. So you're talking about coolant leaking from the front and rear passages, that are on the outermost part of this intake arrangement.

NOTE: I believe this photo BELOF of Mahle's offering is the IMPROVED aftermarket design.


MS15985-ZZ1-03-21-11__ra_p.jpg


The Factory is One Huge Aluminum Tray covering both heads as well as front and rear valley gaskets.

b3udQh8.jpg

QUESTION: Why do I find examples of this OEM/Factory style "valley pan" gasket with the rear coolant passages blocked as in the ABOVE pic, and yet when looking at individual gaskets like the Mahle/Victor they are open???


I would be really grateful if you took pics and did a write up if you ultimately go this route.
It would be great to see (via photos) what is in there on a real engine, as opposed to a drawing in a manual.
 






Thanks for your help Dave. Looked at Imgur....could spend all my day on there!! Hopefully not! But I will be working more on this issue over the next few days so will update what I find. Really don't want to pull those cylinder heads unless it's completely necessary. Lots of other vehicles here to work on also. Those gaskets/seals for the plenum won't hold much air pressure so am probably only going to apply about three to five pounds of air to test for leaks. Bubbles in the radiator....that's the passage with the problem.
 






20190620_173429.jpg
20190620_164008.jpg

If you need any pictures this is the current condition of my OHV
 






Really don't want to pull those cylinder heads unless it's completely necessary.

Using pics from another poster on the forum - ranger7ltr - I see what you mean about not having to pull the heads.

What a total PITA to lift "factory sealed for 23 years" heads up and off the front & rear centering pins on the block!

@Exploring XLT - Thanks for the "exploded" view/pics of the plenum components!

BTW - due to their placement - I imagine that there's no ball and chain in your life ;)

index.php
 






I see what you mean about not having to pull the heads.

Yep....looks like what I have. My biggest issue with pulling those heads is that my exhaust manifolds are not likely to come off easily. The photo shows the manifolds removed and left in the engine bay. I doubt will be the case for me if I pull those heads and I will have to eat dirt, lying under the truck grinding off the bolts to the "Y" connector. Not something I look forward to doing! So...for me, pulling the heads is a last resort. With positive leak down test results, I am hoping that the coolant leak is in that aluminum intake manifold somewhere. Otherwise...I will be eating some dirt I guess.
 






@Exploring XLT - Thanks for the "exploded" view/pics of the plenum components!

BTW - due to their placement - I imagine that there's no ball and chain in your life ;)
LOL, that is a very astute and accurate observation.
 






Cracked heads on the 4.0L OHV engines are quite common. That's my guess. They tend to crack between the valve seats. The cracks are tiny and can even close once the engine heats up. The fix is new heads, but you might want to give an additive called K-Seal a try. Many 4.0L OHV owner's here have tried it with success. While I'm not a believer in "repairs in a bottle" I've used it multiple times on my V8's with front timing cover coolant leaks (also common on the 5.0L) with great success.

As far as your hose and radiator leaks, the only fix is to replace them. When hoses start leaking it's because they rot from the inside-out and plastic-tank radiators fail because the tank end-seals start to leak, or because the plastic tanks crack.

If you want to keep your truck on the road long term, replacing the heads, hoses and radiator is the solution, but the K-Seal might buy you some time on the heads. I used it in our 2000 Mountaineer V8 probably 5 years ago and it stopped my coolant leak ad it's never returned. It also worked in my 2000 XLT V8. K-Seal is sold at most auto parts stores and is around $14 for a small bottle. It's wont hurt any thing and is considered a permanent fix (at least until the system is flushed).
 






@ND Ford where and how are you measuring the coolant loss? At the radiator cap or the reservoir bottle?
 






For some early OHV years, the lower intake had a coolant crossover at the rear as well as the front. Thats why the stock gasket is sealed at the rear but the aftermarket is open. If you have a newer engine with no rear crossover, the aftermarket open ports would just dead end into the aluminum lower intake. Nothing to worry about. I'm using the Victor gasket like this.

QUESTION: Why do I find examples of this OEM/Factory style "valley pan" gasket with the rear coolant passages blocked as in the ABOVE pic, and yet when looking at individual gaskets like the Mahle/Victor they are open???
 






For some early OHV years, the lower intake had a coolant crossover at the rear as well as the front. Thats why the stock gasket is sealed at the rear but the aftermarket is open. If you have a newer engine with no rear crossover, the aftermarket open ports would just dead end into the aluminum lower intake. Nothing to worry about. I'm using the Victor gasket like this.

@FijiBill

Wonder what year they (FORD) made that change to the coolant flow on the 4.0 OHV?

From the pics, the "redesigned" aftermarket Victor/Mahle Aluminum Gasket (Post #9 Above) sure looks like it's built for the long run!

I've seen original FORD / Germany Gaskets on Ebay. They're made out of the Green Teflon Paper (same as the Original/OEM timing cover gasket) and the sealer is spread around the ports VERY thin and not so tall.
 






I don't currently have a vehicle with the 4.0 OHV engine, but rather it's predecessor, the 2.9, which does not have coolant routed through the intake manifold. I'm considering a 4L swap, but in the interest of plumbing simplification and reliability, I'd want to continue with a "dry" intake. I can't find anywhere that this has been discussed. Is it possible? Has anyone actually done it?
 



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I agree with Koda2000, it sounds like cracked cylinder heads. I have a 2000 Ranger that back in March 2016 I had to replace both cylinder heads due to both being cracked. I had a problem with the cooling system kept loosing coolant & about every 3-4 weeks the spark plug of #-1 cylinder would foul out. Here are some pics from when I replaced the heads.
100_0971.jpg
100_0974.jpg
100_0976.jpg
100_0977.jpg
 






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