Leaks and Misfire 1998 K2500 7.4 454

[Crussell45]

I am beginning to acquire some leaks and a random misfire...

I believe I've gotten a motor oil leak. (I have new oil cooler lines.)
I believe I'm leaking coolant... not sure from where. it's a mess underneath... Any ideas where to start looking?
I have something leaking above my brake pedal????
Master cylinder reservoir is leaking.. just replace the reservoir?

Now the misfire....

I had a P0300 code, but it ran fine. So I replaced wires and plugs. While I was doing that, I noticed a hose for my egr was disconnect from the bottom of the air intake, so I put it back on. Now the next day the SERVICE ENGINE SOON light has went off... BUT now I've had a few hard starts... had to give it some gas to start...

167,000 and it has not been drove very much in the last few years.


EDIT--
Yesterday evening I had another hard start. This morning though it had no problem!?!?!?



ALL ADVISE IS APPRIEATED!!

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[Schurkey]

I believe I've gotten a motor oil leak. (I have new oil cooler lines.)
I believe I'm leaking coolant... not sure from where.

How old are the rad hoses, heater hoses, water pump, and intake-to-cylinder-head gaskets? Truck have the OEM spring-type hose clamps, or the hateful, crappy worm-gear abominations sold at every parts-store in America?

Get a cooling-system pressure tester from the Loaner Tools selection at a local parts store. Drive the truck onto a clean sheet of cardboard. Pump the thing up to 16 psi, and see what starts dripping, and where the cardboard gets wet.

it's a mess underneath... Any ideas where to start looking?

It helps if you blast the slime off the engine/undercarriage at the local self-service car wash first.

Add fluorescent dye to the various fluids--engine oil, PS, radiator, (if needed) and transmission. Drive twenty, or a hundred miles. Rent a UV/black-light leak detector from that loaner-tool program, see what glows. Make sure the UV light you rent, and the fluorescent dye all work at the same frequency. I guess some dyes don't fluoresce with some UV lights--the light doesn't glow at the same frequency that the dye does.

I have something leaking above my brake pedal????

INSIDE the cab? As a rule, brake fluid doesn't leak out the back of the booster. Sure it's not a rainwater leak from bad windshield adhesive or a rusted cowl?

Master cylinder reservoir is leaking.. just replace the reservoir?

When that was my truck, I replaced the entire master cylinder. Bench-bleeding the "new" master takes more time 'n' effort than most folks realize, and you WILL need a scan tool to bleed the ABS during the brake fluid flush.

I had a P0300 code,

Is your scan tool capable of displaying cylinder-specific misfire codes? Can it display misfire COUNTS for each cylinder?

Some scan tools LIE about the code; they display "generic" codes (P0300) instead of the REAL code (P0301--P0308).

The Vortec distributor caps are notorious for failure, and I'm told that often it's burnt insulation on the #3 terminal. Consider a new cap 'n' rotor to go with the plug wires and plugs. The Vortec vented distributor cap from United Motor Products has lots of fans on this site.

UMP Distributor Cap – DC-820X - United Motor Products

Distributor Cap

unitedmotorproducts.com

now I've had a few hard starts... had to give it some gas to start...

Cold, or hot?

Hot-start issues are--I'm told--often due to leaking fuel injectors on the Vortec 7.4L. Which hits close to home since my own '97 has that problem.

If this is a cold-start problem, I'd be checking the fuel pressure during the prime cycle when the key is turned from "Off" to "Run", and verify ALL the sensors especially coolant temp, and TPS using a scan tool.

Either way...a fuel pressure test is a good idea.

 

[GoToGuy]

Define " give it the gas " . Did you pour gas down the throttle body? Pumping the throttle does not work. There is no accelerater pump squirting fuel. Ignition should include cap and rotor. Fuel filter lately?

 

[Crussell45]

How old are the rad hoses, heater hoses, water pump, and intake-to-cylinder-head gaskets? Truck have the OEM spring-type hose clamps, or the hateful, crappy worm-gear abominations sold at every parts-store in America?

My guess is most of it’s all original..

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INSIDE the cab? As a rule, brake fluid doesn't leak out the back of the booster. Sure it's not a rainwater leak from bad windshield adhesive or a rusted cowl?

It is most definitely some sort of oil. It’s leaking onto my floor mat. I’ll post a picture.

Is your scan tool capable of displaying cylinder-specific misfire codes? Can it display misfire COUNTS for each cylinder?

Some scan tools LIE about the code; they display "generic" codes (P0300) instead of the REAL code (P0301--P0308).

It was just a scanner from the local tire shop.

Cold, or hot?

Hot-start issues are--I'm told--often due to leaking fuel injectors on the Vortec 7.4L. Which hits close to home since my own '97 has that problem.

If this is a cold-start problem, I'd be checking the fuel pressure during the prime cycle when the key is turned from "Off" to "Run", and verify ALL the sensors especially coolant temp, and TPS using a scan tool.

It does all most every time it’s warm… and I say warm cause I haven’t checked to see it if it’s doing it at operating temps.
It does not do it very often when it’s cold.


How would a guy check the fuel pressure?

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[Schurkey]

My guess is most of it’s all original..

It's all suspect, except maybe the spring clamps.

It is most definitely some sort of oil. It’s leaking onto my floor mat. I’ll post a picture.

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Does this vehicle have Hydroboost? Kinda guessing PS leak, not brake fluid.

It was just a scanner from the local tire shop.

Doesn't tell us much.

It does all most every time it’s warm… and I say warm cause I haven’t checked to see it if it’s doing it at operating temps.
It does not do it very often when it’s cold.

Long cranking when hot is classic "injector leaking" symptoms. My '97 7.4L does the same thing.

I'm not saying it CAN'T be something else, just that this is common.

How would a guy check the fuel pressure?

With a fuel pressure tester borrowed from a local parts-store "Loaner Tool" program, and following the instructions in the Genuine GM service manual set, downloaded from the links in the Sticky Thread section of this web-site.

 

[Carlaisle]

If you have the original injectors and 167,000 miles on the odometer there's a 99.99% probability your long start when the engine is not cold is bad injectors. They were junk when they were new and they haven't improved with age. If you want new, fiveomotorsports has them for a not insignificant sum. You can also use some of the LS injectors. Don't bother spending money on anything that looks like what is already in there. That style injector was junk in 1998, it's junk now (whether new or "reconditioned"), and it will be junk at all times in the future. Many will fit, most will require tuning. I have posted part numbers in the past that are drop in replacements, no tuning required. Many will tell you to replace the fuel pressure regulator (FPR), but it is unlikely to be bad. You definitely should replace the tiny piece of hose that provides vacuum to the FPR. You should also be very careful when replacing those injectors because the fuel rail they are attached to is no longer available from anyone at any price. Many people here can provide first hand advice on how to proceed if you choose to do so.

 

[Spareparts]

That leak inside is from the Hydroboost. Mine had the same leak. It's power steering fluid.
The easy way out is to get one off Rock Auto. The hard way is to fully rebuild it as resealing it from the front will not fix it.
I flushed the system and installed a PS filter, then i change it for a new Hydroboost. Leak gone.

Many posts on how to change injectors so i'll skip that but 1 piece of advice i never see mentioned is to add a drop of oil to each clip where it snaps onto the rail and pry here where i have marked with red arrow.

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[454cid]

Hard stating could be low fuel pressure. You could also have injectors that are leaking.