2.9L Head Gasket replacement

[brdeca]

Does anyone know of a good article/forum post/video that walks through the process of replacing head gaskets on a 2.9L Cologne? I need to replace the gaskets on a 1986 Bronco II and I can't seem to find anything super thorough or detailed. I know I can figure it out with the information I can find but the more help I could get the better. Thanks in advance!

 

[gaz]

-Remove the exhaust manifolds
-Remove the air inlet and throttle/body
-Remove the upper intake manifold
-Remove the valve covers
-Remove the distributor. Make note of the position of the rotor and the position of the distributor (you could make them with a machinist's scribe or Sharpee)
-Remove the lower intake manifold
-Remove the rocker arms
-Remove the pushrods and lifters (keep track of where they can from, put them back where they came from)
-Remove the heads
-Thouroughly clean the block surface
-check the block and heads for warpage
-place new gasket on alignment studs

Reverse removal process for remaining components, after a proper clean/inspect. New head bolts must be used, the rest of the hardware must be cleaned, inspected and evaluated prior to reuse.

I recommend Stage8 locking header bolts for install; torque them once, FOREVER!

 

[Shran]

Pretty good chance that you're dealing with cracked heads and not a simple leaking head gasket - factor a pair of heads into your repair cost.

 

[Cees Klumper]

Mine has started to make coolant disappear. Not sure whether it is getting burned off in the exhaust, a tiny amount seems to end up on the oil filler cap (but really little, and could also be unburned condensation, I do a lot of short trips these days). Oil level is steady, so it's not really going in there. It's not the heater core as I would smell that, and the carpets etc are dry. Car doesn't smoke either. Still, if I fill the overflow tank to the 'full cold' level, within a week or so it will be down to the bottom of the canister.

Is it possible I only need new gaskets? Or is it usually the case that one or both of the heads need replacement when these symptoms occur? To the best of my knowledge, it has not overheated at all (and still doesn't, engine runs good and strong). No coolant under the car ever. So am a bit stumped.

 

[ecgreen]

Whatever ends up being wrong, If I you strip it down to the heads have them magnafluxed. I personally would not put any used 2.9 heads on my engine unless I had them checked by a machinist for cracks.

 

[Shran]

Mine has started to make coolant disappear. Not sure whether it is getting burned off in the exhaust, a tiny amount seems to end up on the oil filler cap (but really little, and could also be unburned condensation, I do a lot of short trips these days). Oil level is steady, so it's not really going in there. It's not the heater core as I would smell that, and the carpets etc are dry. Car doesn't smoke either. Still, if I fill the overflow tank to the 'full cold' level, within a week or so it will be down to the bottom of the canister.

Is it possible I only need new gaskets? Or is it usually the case that one or both of the heads need replacement when these symptoms occur? To the best of my knowledge, it has not overheated at all (and still doesn't, engine runs good and strong). No coolant under the car ever. So am a bit stumped.

It would probably be worth doing a leakdown test or at least pull your plugs and see what they look like. If one or more look super clean, almost "new" looking like they got steam cleaned, your coolant is burning off. But it could be just an external leak too. Upper intake, thermostat housing, water pump, hard to say.

I will say that I sold my buddy a core 4.0 motor that seemed to run really well. No smoke, plenty of power, no evidence of coolant loss. He just wanted a block to rebuild. The machine shop found that both heads were cracked in multiple locations and it was likely burning a small amount of coolant.

2.9s rarely need JUST head gaskets... if there is a coolant loss issue, 99.99999% of the time there is at least one cracked head.

 

[Cees Klumper]

Ok thanks, may just bite the bullet then and order rebuilt heads, they are not super expensive. But will check the plugs first, thanks for the tips!

 

[Cees Klumper]

So yesterday I started taking off the heads. Lots of coolant gunk in the valve covers but as I got to removing the intake manifold I noticed several of the bolts holding it down weren't tight, in fact I could undo them by hand! I proceeded to remove one head, which looked fine. As I researched a bit more, I read that a loose intake manifold can also cause coolant leaks into the engine/oil. Before I take the other head off, should I just try a new intake manifold gasket, put it all back together, and see if that solves my coolant leak? Or should I, now I am into it this far, go all the way and put in reman heads, head gaskets etc? It's clear someone was in there before, there's replacement head gaskets, they completely left out exhaust manifold gaskets (so I can see those have been leaking), the loose bolts on the intake manifolds etc. The engine was still running really strong, with that coolant leaking in, no compression loss it seemed. What would you do if you were me at this stage? I would like to avoid the extra expense and wait time of putting in hew heads etc., it really seems my issue was the loose intake manifold (through which the coolant enters the engine) rather than a bad head / gasket. Thanks for your advice!

 

[Shran]

I would be awful tempted to try and clean it up really well, put new intake gaskets in and see how it runs. You will only be out minimal expense for a gasket set, fluids and time... Worth a shot!

 

[Cees Klumper]

Thanks a lot - I ordered a complete head / intake / exhaust manifold gasket set and head bolts ($156 in total) for pickup later today, hopefully today I can put it all back together, replace the engine oil and coolant and then, fingers crossed!

 

[Cees Klumper]

Spent most of yesterday and today replacing the head gaskets, intake manifold gasket, and re-assembling the whole shebang back together, with new head bolts. Silly thing was I had marked the distributor orientation on the intake manifold with white-out, but then washed off that mark when I cleaned the oily gunk off the manifold, heads etc with kerosene. So it would not start at first, until I played with the ignition timing until it did start and I was able to set it properly (spout connector removed).
I reset all the valve lashes while it was all open, some were out a bit, one a lot. Took a 7/16 inch socket rather than metric for some reason. All the plugs looked fine and so did the combustion chambers, valves, and pistons. One cylinder wall had some light scoring. Don't know if it's the original engine (only bought it in October 2019) but the truck does have 235K miles on it. The heads have been off before, the old gaskets were the exact same Fell pro I used.
After I got the ignition timing set, and the coolant system filled up, the engine ran good, although it seems to be re-setting the idle (it's sorta high, say 1,100 rpm, then drops one second to the next to around 650 rpm which is too low). Until I got the coolant topped off it started running rough as the engine temp climbed, and I got a 'check engine' light briefly but after getting almost another gallon of coolant into the system, it seems to be settling in ok.There's a small exhaust leak at one (or both) of the manifold-to-downpipe connections that I hope to seal up after it has all cooled down, tomorrow. No coolant in the oil filler neck so far, but it was only a 5 mile test (and beer) run, so only time will tell if I actually fixed the coolant leak, after all of that work. It did take me two solid days, but only $156 in parts, so not bad in the out-of-pocket department (not counting the oil and filter change I also did, just to make sure there was no coolant left in the engine). BTW I found I had to also remove the AC compressor and alternator, just to get at things and be able to take the heads off. Also, when removing the exhaust manifolds, two of the bolts snapped off, so that took time drilling out the bolt remnants and tapping in new threads, getting new bolts at hardware store, etc.
Fingers crossed the coolant leak is fixed and the idle settles back to where it should be. I really love this Bronco II truck. There was a procedure somewhere on re-setting the idle, may have to look for that.

 

[Cees Klumper]

So today, after the idle just not settling right on some test runs, and I even got a check engine light again, decided to look once more for a vacuum leak. Sure enough, found it: I had not connected the thin vacuum line for the air/heat flaps or what have you. It connects, on my car at least, to some hard-to-spot vacuum port away from the 'tree' that most other lines connect to, and the line itself had also literally dropped out of sight because of all of the component and wiring removal I had to do to remove the heads. Reconnected it and, presto, silky smooth idle is back, lots of pep and all seems well in general.
Will be monitoring the coolant and oil levels closely, checking under the oil filler cap etc for traces of coolant. No external oil or coolant leaks, the new valve cover gaskets seem to be doing their job. The old ones were rubber, and had additional sealant on them; the new Felpro ones are cork and I did not put any sealant, just ckeaned off the mating surfaces really well. .

 

[Cees Klumper]

Quick update, ran the truck on the highway, maybe 30 miles, and so far the coolant is holding steady, and no trace of it in the oil filler cap (before my intervention of replacing head and intake manifold gaskets + torqueing everything down according to specs) the coolant would drop fairly quickly, i.e. emptying the entire overflow reservoir, in about 50 miles. So I don't want to jinx it, but so far so good. Engine also is quieter, as the PO failed to put in any heads-to-exhaust manifold gaskets - they were just bolted on metal to metal and I could see exhaust gasses had been escaping routinely. I also found another very small vacuum leak this morning, a very small diameter vacuum hose that had broken, near the blower motor so close to the firewall on the passenger side. This vacuum hose (only like 3 mm diameter) disappears into a wiring loom and I have no idea where it goes. Now, the truck shifts smoother, before it would shift a bit abruptly into second when accellerating without a lot of throttle - I have come to appreciate that vacuum leaks, even small ones, can have a major impact on how the engine and trans work. I will post another update when I have done a couple hundred more miles.

 

[dccarpenter]

They have a tester that fits on the radiator cap that fills with fluid, the fluid changes color if their is exhaust gas in the cooling system. This can also be a useful tool for testing for a cracked head or head gasket.

Good to hear that it sounds like you solved your problem without replacing the heads. I had coolant disappearing with no leaks or coolant in the oil as well on my '88 2.9 ranger, I ended up just using the Blue Devil sealant in my cooling system as I couldn't take the truck apart at the time. It seemed to solve the problem for the next 5000 miles until I sold it(I disclosed the Blue Devil use to the buyer..)

 

[Cees Klumper]

Thanks, I was actually looking at that tester at HF this afternoon; decided to hold off until I have driven more miles. Encouraging was that, so far, coolant is holding steady at exactly the same level and also 0 coolant in the oil filler cap (where it kept appearing before my intervention). But I for sure will get that tester if necessary, it was only like $50.