Coolant Loss - Rough Idle - 4.0 OHV - Head Problem??

[Jim Jermain]

I have a '00 Explorer with the 4.0 OHV. I've been chasing a rough idle at cold start for two years. After about 30 seconds the truck runs great. I've changed just about everything possible (plugs, wires, upper & lower intake gaskets, IAC solenoid, TPS, EGR solenoid, fuel filter, fuel injector, injector o-rings). I've checked the fuel pressure, I've checked compression, and vacuum. I've also sea-foamed the engine and cleaned the Mass Air sensor.

I am losing some coolant with no visible signs of external loss. I do occasionally post a cylinder 3 misfire. I also noticed when I tried to remove the number three plug the threads were coated with a black hard substance. It didn't look like oil, more like carbon. On one of the posts I read about sliding a small cotton rope into the cylinder to see if it comes out with any signs of coolant. I did not see any signs of coolant after letting it sit overnight.

I've read a lot about leaking head gaskets and cracked heads on these engines. Any suggestions on whether my coolant loss and rough idle might be associated with a cracked head or bad gasket? Any tips on how to confirm?

Thanks,

Jim

 

[ranger7ltr]

Unfortunately this does happen...

The best way to see if the heads or gaskets are leaking would be to get a cooling system pressure tester and see if the head or gasket leaks when you pump it up...IF you suspect a particular cylinder, I would pull plugs out and then pressurize the cooling system for confirmation...Hissing sounds or coolant spray will be evident...

I have also seen coolant leaking externally between a head and block from the head gasket and the leak did not show up at all...The only sign was a discoloration at the joint between the two and the area was dry...

You didn't mention how much coolant you are losing so I would also check at the heater control valve and the water pump inspection hole for leakage as well...And do you see water in the oil or oil in the radiator?

If one or both heads are leaking/cracked/fouled somehow, replacement of the heads with aftermarket units is the best and more economical way to go...They have thicker castings so they don't crack like OEM heads and the valve components are all new as well... Plus they came with a 1 year warranty...

 

[Jim Jermain]

Thanks for the great tips. I will try the coolant pressure test. As for the amount of coolant loss, it's not that much, maybe a 1/2 quart every 3K miles.

Jim

 

[dz]

My 97 sport 4wd OHV 4.0 had a initial rough idle start up then would clear up within 10-20 seconds and would be fine for the rest of the day until next cold startup. I took my heads off and noticed I had a crack on a valve bridge on each head, the cracking valve bridges seem to be a common problem on the OHV engines. Got rebuilt cylinder heads and all new upper gaskets now she runs like a top. Hopefully good for another 100,000 miles.

 

[clamb]

I had a 1999 Explorer XLT 4.0 l OHV with an external coolant leak from the intake manifold gaskets. Took it to the dealer to repair & it didnt make 100 miles before seizing the engine. Aparently the dealer never replaced the oil after doing the intake manifold. Anyhow I had to repalce the engine at my cost, as well as the repair bill for the leaking intake manifold gasket. If you are concerned you can do an oil analysis on your next oil change.

The rebuilt drop in lasted for about 80,000 kilometers & I blew another head gasket, hydrolocking the cylinder so it would not turn over. I thought the engine was seized, but I removed the spark plugs & shot coolant out all over. Right now I am running on the 3rd engine as well as a rebuilt tranny.

 

[joe doe]

sounds like a head crack to me jim .
you probably read the rope trick in my head crack thread.i am having this issue right now .cyl number 4 on mine .plugs last about a month ,then the insulator cracks and its shot .

replace plug and we start over again .

at least you are catching it now ,not like me "after" i done all the head gaskets.
backwards progress over here .i would have thought my mechanics would have seen a cracked head during the head gasket repair?

but not so...now i am stuck putting new heads on a 145,000 mile block and eating the costs all over again .

i am still losing coolant and have the rough idle at near every start now.

ford should have redesigned the heads and gave everyone new heads .but i guess since they dont normally fail until after 100,000 miles they were not concerened with it .

 

[BIGTREAD]

Okay folks, these systoms sound like my own. No 3 misfires on start up. Used to work to replace plug that was chewed up. Runs fine after 30 seconds. Having weird coolant problems too. Overheating, then cool fluid gushes from the cap when I open it up.

What cost should I being expecting for new heads installed??

 

[Betsy98Sport]

Thanks for the great tips. I will try the coolant pressure test. As for the amount of coolant loss, it's not that much, maybe a 1/2 quart every 3K miles.

Jim

Did you ever resolve this issue? Same issue is occuring in my 98 Sport 4.0 OHV

 

[RomeovilleIL]

The fix requires new gasket at minimum, usually with machined or new heads. If you dont have the ability or cash right now, a lot of people have very good short term (like 6 - 12 months) results with a can of barsleaks or other radiator stop leak. Will usually run great afterwards, but you will still need to get it fixed right sometime soon.

 

[Betsy98Sport]

The fix requires new gasket at minimum, usually with machined or new heads. If you dont have the ability or cash right now, a lot of people have very good short term (like 6 - 12 months) results with a can of barsleaks or other radiator stop leak. Will usually run great afterwards, but you will still need to get it fixed right sometime soon.

The problem is I had this last summer and then replaced all gaskets and heads. It ran great from last September 2010 to around July 2011 and then started to do it again around July to August 2011. So I'm wondering if it's worse. Is it the same problem or something new? The coolant is low again like before and the rough idle is there on cold start and you can feel the misfires as you drive.

I discovered a leak on the outside last time right at the head gasket so that made it obvious. This time there's no obvious leak. I also replaced the timing cover gasket and water pump gasket at the time as well.

I assume I should do what I did before and diagnose with a coolant pressure test and compression test? Do you agree?

 

[RomeovilleIL]

Yes, same test procedure. Makes me wonder why would get a leak on 1 year old repair assuming new parts?

 

[Betsy98Sport]

Yes, same test procedure. Makes me wonder why would get a leak on 1 year old repair assuming new parts?

I'm wondering the same. Brand new heads and all new gaskets (Fel Pro gasket kit) and now the same issue.

Almost seems worse because last the misfire went away after a few minutes of the engine being started but now there are misfires throughout the whole drive.

I'm always weary about putting stop leak products in my cars so I dont know if Im going to do that yet but then again I dont feel spending $500 to fix it all again.

I dont think the heads would have damaged. They were reinforced more so than the originals and the truck never overheated.

 

[countryboy541]

I loved my fords to death and I believe in the 4.0. I have a coolant and a rough idle and instead of spending the $500 or so on new gaskets, heads, and bolts I am just dropping in a used motor. Its a crying same ford didn't follow suit with gm.gm to the classic 350ci and cut two cylinders out thus making the 5.7 v8 into the 4.3 v6 which is an awesome motor

 

[Betsy98Sport]

I loved my fords to death and I believe in the 4.0. I have a coolant and a rough idle and instead of spending the $500 or so on new gaskets, heads, and bolts I am just dropping in a used motor. Its a crying same ford didn't follow suit with gm.gm to the classic 350ci and cut two cylinders out thus making the 5.7 v8 into the 4.3 v6 which is an awesome motor

How much is the motor running you? (junkyard pick up I take it)

 

[countryboy541]

$250 from a local wrecking yard. I work for a repo company and my boss used to own a wrecking yard so we still get all the discounts and perks.before the swap im going to put in new spark plugs, intake, valve cover gaskets and oil pan gasket to cover my bases. Im pretty sure my currant motor has either a blown head gasket or cracked had. Its the 4.0 in a 91 Mazda navajo

 

[Betsy98Sport]

$250 from a local wrecking yard. I work for a repo company and my boss used to own a wrecking yard so we still get all the discounts and perks.before the swap im going to put in new spark plugs, intake, valve cover gaskets and oil pan gasket to cover my bases. Im pretty sure my currant motor has either a blown head gasket or cracked had. Its the 4.0 in a 91 Mazda navajo

Sweet deal on a motor!