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Totally Stumped


Tedybear

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Think I'm coming to the end of my run with this 2.9

No way I can afford to swap to another engine, can't afford to throw mega bucks at this engine. This one just seems to be slowly going downhill.

Here's the deal. Maybe someone can help me make sense of this.

Several things in the past I've been trying to work out.

First is the odd 'white' smoke that appears upon starting the engine. Takes a few minutes after it starts--It slowly goes away after a few minutes. If I drive the truck daily? This white smoke isn't quite as bad. Leave the truck for a few days? And it's pretty bad.

I've had a pressure tester on the radiator--It seems to hold pressure and does not look like anything is leaky (other then the heater hose on the water pump has a slight seep)

Start the engine up and remove the radiator cap when the engine is stone cold. It burps out about a cup of anti freeze. It acts like there's pressure, but there are no bubbles present, nor any exhaust fumes. Didn't think that much of that test, as I've seen that a lot on older cars/trucks. Plus when the cap is off? The coolant doesn't start spilling out after that first 'hiccup' (now let it get to the point the thermostat is getting ready to open? And then it starts to expand and dump a bit. Again, normal from what I've seen from other older engines..once the stat opens? Then the level drops a bit and holds.)


When the engine starts up, it acts like it has one or two severe misses. It also seems to bog down badly. Same if you start it and then try to drive before it has a chance to hit "closed loop" (aka, warmed up all the way) It runs like an ignition skip--bogs down... Once it gets to temp? Everything seems to run fair...the engine retains a slight running rough idle, but is responsive. When it shuts off--the engine does so roughly.

When cold the engine also has developed a really bad idle surge. First start it up---and it goes from 1400rpm down to 900....almost like in cycles. Did not find any sign of a vacuum leak (had the same thing happen a few years ago--turned out to be the check valve in the booster and the rubber seal went bad. Replaced both, checked good)

What's been done so far, and recent replacements:

Installed a new thermostat back to 195 (used to be 180-185) Problem seemed to get worse....but it wouldn't explain all this stuff happening with a cold engine.

Pulled injector rail and manually cleaned all injectors.

Checked fuel pressure. Holds 32lbs at idle and when line is removed holds 42 lbs. No sign of fuel in the vacuum line.

Compression checked. All cylinders reading 160-170ish. Nice and even.

Spark Plugs checked, rechecked, checked..... All slightly worn--but still in excellent condition. Drivers side front plug was the only one that looked 'odd' with a matte black finish on the tip. The rest all had a light shade of gray. No sign of 'carbon' or soot. (black matte finish is clearly not 'flack' carbon....more like someone took a magic black marker to the plug tip)

Vacuum checks as follows: Upon first starting the engine struggles to hit 18ln. Holds an even 15ish....warms up and stops stumbling and holds 18-19 even. It still acts like it's being "held back" when taking out for a test drive when cold.

CEL is not on during any of this. I have yet to pull codes, but the CEL has never come on, except during the start up self test bit.

I've used a mechanics "ear" and started the engine up and listened to each injector to ensure they are firing. All have a pronounced "tick" as expected.

Did a power balance test--did get shocked by one of the plug wires. When examined while running this plug wire is not arcing to ground--it was the plug wire removal tool that bridged the gap with the pin hole to ground. I mention this in passing, as it was recent with the tool nipping the boot. (It was doing this odd running stuff prior)

Pulled the cap and inspected for carbon tracking...didn't see anything odd.

Clearly "water" is getting somewhere into the combustion system. I can't figure out where. The engine seemed to "hydro" lock a few weeks back, it cranked 1/2 a turn and seemed to lock up. It finally started up, did it's white smoke bit..and ran decent afterwards. I checked and double checked, and can't see where any coolant is leaking into the system.

As a side bar note. I did have to wonder about about maybe the map sensor? So I had the engine running..and pulled the vacuum line. No sign of any 'gel' in the line--and the engine died soon as the line removed. (it would not restart until I reattached the line.)

The TPS was replaced a little while ago--so that part should still be decent. And it does not show any sign of 'dead spots' when I'm driving.

As a further note. The converter(s) are fine. This problem has become worse over time--and I did have the muffler off recently to replace it. I had a good look at the converter bed, and it's good. No sign of any restriction with the exhaust.

At this time I'm pretty well spent. The only other thing I can think of is just saying screw it and replacing the intake manifold gasket--maybe the head gaskets.. I'm just tired of throwing parts at this enigma.

Any ideas or suggestions? Please let me know. I can't afford the $$ to throw parts at random anymore. Sorry if this seem a bit random, but I went off memory so far and it was hit/miss and I wanted all the details to be good.

S-
 


Tedybear

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I'll have to answer my own post it seems!

LOL


Well..

Left the old girl sit for several days. Decided before tomorrow I would pull the plugs and once again spin the engine over and see if any coolant was present in the cylinders.

All plugs totally bone dry.

Peeked at the engine fan so I could rotate it in the right direction. (Yeah I know...I should know this LOL. But it was a long day at work) So I grab a belt and start a tuggin' Pretty easy with the spark plugs all removed.

I get about 3 pulls on it...and the cylinder I thought was suspect? Totally GUSHED out about 2 cups of coolant. Soooooo I found exactly where the problem is. (drivers side all the way forward)

I continued to spin it around a bit more and it's the only one that is internally steam cleaning my exhaust system.

Next plan of attack would be for me to drive it over to the garage I work out of. (Yeah, I can still drive it. Oddly enough once the cylinder was blown out dry? Ran pretty good LOL)

I'll pull the intake manifold and inspect the gasket and manifold. From what I've gathered, the coolant passage is less then 1/4 of an inch (maybe more like 1/8th of an inch looking at the photos) away from the intake runner. Looks like this finally surfaced.

S-
 

alwaysFlOoReD

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Sorry about your luck. But thanks for letting us know what was wrong.

Richard
 

Tedybear

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Sorry about your luck. But thanks for letting us know what was wrong.

Richard

The intake gasket kit's pretty cheap from RockAuto. I went with Felpro when I did the install several years ago. I'll probably go to a cheaper brand due to $$ being uber tight. I think the fail, if the intake gasket is the issue? Might have been due to my installation. Might not have prepped something just right....didn't get the torque dialed in right...etc..

Just going to order in the gaskets, and follow the install instructions to the letter. I'm actually relieved the issue finally surfaced. And it makes sense the engine would run a bit rough--if the engines vacuum is also drawing in a small portion of coolant when it's running. Talk about watering down the mix!

At least my converter is "Steam Cleaned". (seriously...that thing when I examined the 'bed' when I did the muffler? Pretty darn clean!) Just not how it should be maintained...

Maybe I'll do some photos :D

S-
 
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RonD

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Glad you localized the problem.
Can't figure out why the cooling system pressure test didn't show a leak.

You seemed to have done everything correctly, test wise, so very odd indeed.
 

Tedybear

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Well to be honest, the pressure tester from advance auto sucks rocks. Actually that is a dis-service to all the rocks in the world.


If my guess is right, it's the coolant passage right next to the port for the drivers side front. I feel it's a very small leak, just dribbles into the intake valve area. This would explain why the truck always seems to have a slight "sweet" smell to the exhaust, and a trace of white smoke when I drive it. The engine vacuum would be drawing in trace amounts of coolant. Get the cooling system under pressure? And there goes a double hit.

And once I bumped the thermostat back to the stock temp--The slight increase probably meant just a slight amount more of expansion and contraction. Which just made things worse.

One question however. The shop manual states to coat the sealing surfaces, ALL of them with a light coating of sealant when installing. (not just the ends of the intake, but even the ports). Now I can't remember if I did that or not? As memory serves, I think the instructions in the install guide countermanded those instructions, and stated the installed silcone sealant was designed for that purpose, and nothing else is to be added.

I think given just how much of a headache this is becoming--I'll probably put a very thin coating of rtv black or the like on all of the ports, both sides. Just enough so that when everything is compressed---it's darn good and sealed. I just can't remember if I did that or not years ago?

I do intend to re-use the plenum gasket.....once the work is done....run the engine for about 20 minutes just sitting there. And then remove the plenum and re-torque all the intake bolts. Then install the new plenum gasket and torque that down.

The tear down starts on Tuesday. I found a killer deal (under 20) for a felpro intake gasket complete set on eBay. I can get the valve cover gaskets locally.

Any hints or tips this time around? Maybe it would be a good time, sense the push rods will be out---pull the lifters and give them a soak in solvent?

S-
 

freedom5

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I had the same problem about 4 years ago and found it was a blown head gasket. The big danger is that coolant could be getting in the oil. The sweet smell in the exhaust also verifies anti freeze is leaking into the cylinder.
 

Tedybear

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That's the fun part of this engine. Both heads replaced with world products heads. New gaskets....I'll see which one is the issue once I pull the intake off. I suspect I'll see a trail into the valve area.....But one never knows.

I will say this much. There has never been any coolant in the engine oil at any time during this. Each time I've changed it out? 100% normal. Must have a good set of rings to seal that well. LOL.

But it will get a full oil change after the work is finished. Once the intake comes up? Usually there's always some coolant that spills into the valley pan area. Plus if it's leaking at that point? I'm expecting to see just a bit more then a little droplet.

S-
 

sjr53

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While you have the valve covers off, I would advise checking the rocker arm shafts for being plugged up with what looks like black oily sand. I am in the middle of working on a 2.9l on my engine stand to use for an engine swap and found the rocker arm shafts seriously plugged at both ends, starving those rockers and lifters of their oil. The shaft & rockers are slightly damaged, but I'm just going to flip the shafts upside down and smooth the grooves in the rockers. I removed the end caps on those shafts plus 2 extra shafts I have that were also plugged up and cleaned them out. I got 9/16 inch replacement caps and pounded them in place. Maybe you could manage to clean out the shafts without removing the end caps. Before I pull the noisey 2.9l that suffers from collapsing lifters after warm up, I'm going to try putting my spare cleaned up rocker arms on it and see if that fixes the problem.
 
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