In depth motor advice needed
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Senior Member
Joined: Nov 2004
Posts: 132
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From: Virginia
In depth motor advice needed
Ok Motorheads, Last week my 99 F150 5.4L blew a head gasket. Tore the motor out, and down. Replaced all main bearings, rod bearings, rings,
all seals, heads decked, basic overhaul. Evrything went very smooth, until start up. Truck starts fine, motor sounds fine other than the 2000 rpm idle. Checked IAC and functioning properly. All vacuum lines are hooked up and in correct place. Replaced TPS, and Crank P.S. No codes, but still 2000 rpm idle. After having to truck get up to tmperature for the third time ( to burn off oils, and residual water in exhaust) I noticed a small amount of steam. My cylinder heads had to be decked .011 to be true, which is almost an excessive amount. Is it possible that as the cylinder heads warped, they may have warped either the mating surface between the intake and head, or the intake itself. I have had the motor running and sprayed either all around to find the vacuum leak, but have found nothing and the only place that I cannot get to is the right rear corner. This location would be consistant to an intake leak due to the fact that there is a water jacket an that corner. Not to mention that is the only place it can leak water besides the head gasket, and it is not showing up an a compression or leakdown test. I have been building motors for 8 years, and this one has me stumped. Please anyone with any advice or even ideas would really help.
P.S.- This was my first Modular motor....pretty cool stuff when its apart.....
Thanks a ton,
Adam
all seals, heads decked, basic overhaul. Evrything went very smooth, until start up. Truck starts fine, motor sounds fine other than the 2000 rpm idle. Checked IAC and functioning properly. All vacuum lines are hooked up and in correct place. Replaced TPS, and Crank P.S. No codes, but still 2000 rpm idle. After having to truck get up to tmperature for the third time ( to burn off oils, and residual water in exhaust) I noticed a small amount of steam. My cylinder heads had to be decked .011 to be true, which is almost an excessive amount. Is it possible that as the cylinder heads warped, they may have warped either the mating surface between the intake and head, or the intake itself. I have had the motor running and sprayed either all around to find the vacuum leak, but have found nothing and the only place that I cannot get to is the right rear corner. This location would be consistant to an intake leak due to the fact that there is a water jacket an that corner. Not to mention that is the only place it can leak water besides the head gasket, and it is not showing up an a compression or leakdown test. I have been building motors for 8 years, and this one has me stumped. Please anyone with any advice or even ideas would really help.
P.S.- This was my first Modular motor....pretty cool stuff when its apart.....
Thanks a ton,
Adam
Technical Article Contributor
Joined: Dec 1997
Posts: 9,417
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From: Windsor,Ontario,Canada
It could be pooled coolant in the valley. Did you replace the heater tube O-ring that goes to the back of the water pump? As for the idle I would let it idle for 15 minutes so the PCM can relearn the new idle strategy. Turn on the A/C for ½ of the idle time.
JMC
JMC
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Senior Member
Joined: Nov 2004
Posts: 132
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From: Virginia
Thanks, I'll give that a try. The only problem I have with that is I also have a small water leak, only enough to get an occasional miss. I am gonna pull the plugs today and see which one is clean. I will give it a shot to let the PCM "re" learn. Ill let you know....thanks again
