SYMPTOMSNoticed about 2 weeks ago the overflow tank was empty, so refilled it. No external leaks, hoses dry, radiator dry (no leaks on cardboard underneath. Truck has been stuttering and bucking on slight uphill grades in 4th gear with the RPM's under 2K, and downshifting to 3rd raises RPM's and power is back with less stuttering for the past 6 months, leading me to believe the spyder or fuel pump wa on it's way out. Today I was out and about and noticed the temps were 2 marks above 210 and turning the heater ON FULL HIGH (TEMP and FAN with selector set to VENT's) DID NOT DECREASE the temps. Got it home, tripped the lever on the cap (truck running ) and watched the tank. Nothing backed up into it. ReCycled the trip lever. Still nothing. Turned cap 1/2 of travel, still nothing, so removed the cap. Radiator dry about 1/3 way down. Filled with 50/50 mix Prestone. Ran rpms to 1500 and kept adding until full. Vented Prestone kit cap, solid 50/50 mix. OIL LEVEL IS TOTHE TOP OF THE NORMAL ZONE (Changed the oil with Walmart Full Synth 10W-30 and AC DELCO PF-52 last month. Been running this combo since I bought the truck with no problems) with no indications of Antifreeze in OIL. I did drain a cup or so of oil from the crankcase an hour after shutting it down to let it stratify if there was any water in there. NO Antifreeze in the OIL. Engine does have an intermittent miss/stumble @ idle that I have not been able to identify for last 2 years. And it does stumble slightly off the line from a dead stop unless I power brake to approx 900rpm in gear.
RELEVENT PARTS REPLACED
Since I bought the truck in 2007 I've replaced the DexCool with Straight 50/50 after flushing repeatedly with the drains open and installed a prestone kit. New hoses, 170* thermostat, and electric fans from Junkyard in 2008. Went back to stock fan setup with new H.D. clutch back in May this year when I replaced all 3 motor Mounts. With electric fans set to 160* it was running 3 marks below 210 with AC on in summer temps (Md. DC Area). With Stock setup, Temps are now 1 to 1.5 marks below 210, Temps with AC now @ 210 on the mark. I may go back to Electric fans, but get something better fitting. Trans temp (sensor at Radiator output) tracks the Antifreeze temps but about 40* lower, except when AC on then it climbs to Engine temps.
SYNOPSIS
So basically we have NO EXTERNAL LEAKS, Bucking and stuttering at low RPM(<2K) under load, and a full recovery tank of antifreeze sucked up in less than a month. Oil Level is Full with no indications of water in oil. New Fan Clutch, Antifreeze changed yearly, Thermostat and cap are fine, but are 4 years old (change is due soon).
Which leads me to the questions .
1.) With the external connections all dry, and no visible leaks, and no exhaust smoke at steady state unloaded (in park) 3K rpm, or on Deacceleration, what are the chances that the Lower intake manifold Gasket is leaking into the combustion chambers? (I'm thinking pretty high.)
![Idea :idea:](./images/smilies/icon_idea.gif)
2.) Not having torn a 4.3 down before, except to replace the Fuel Pressure Regulator, am I gonna have to disconnect the Fuel spyder from the fule lines or can it be moved out of the way?
3.) Does the Distributor have to be removed to remove the lower 1/2 of the manifold to replace the gaskets?
4.) If the general consensus is the Intake Gasket, which is the most recommended set from FELPRO. The . MS 98002 T OR the MS 95817. I really can't see paying almost $40. for a set of Valve cover gaskets! Unless there is a difference in the intake gasket construction.
5.) Are replacement INTAKE bolts "REQUIRED"? or just recommended? Are they one time use due to construction and a set stretching strength? Or is this another FELPRO "lets sucker the folks into another $30. for bolts they really don't need?
Now that the wife is retired, and I'm on permanent disability, This crew along with the '95 Jimmy will probably be the last vehicles I ever own. I don't plan on getting rid of either. Not when i can get between 24 and 26 on the Hwy in the Jimmy on a long trip. 62mph, 13" on the vac guage and coasting down every hill I can. The ZR-5 gets 22-23 doing the same. Maybe fixing the problem will get the wife out of the Jimmy and into the ZR-5.
Thanks in advance for any and all help.
Larry