MajorCommonEngine

Holden Rodeo: Injection pump drive-end seal leaks diesel into the engine oil (4JA1 / 4JB1 / 4JB1-T)

Injection pump drive-end seal leaks diesel into the engine oil (4JA1 / 4JB1 / 4JB1-T) is a common engine fault on the Holden Rodeo on the 1988–2002 cars, and we rate it major. Putting it right costs $800 to $2,200 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 12 documented faults on the Holden Rodeo.

Vehicle: Holden Rodeo
Engine: 4JB1-T / 4JA1 / 4JB1
Years: 1988–2002
Fuel: diesel
System: Engine

This page covers the Holden Rodeo as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Holden Rodeo faults12 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the High-pressure fuel pump yet. We would rather show none than show a picture of a different part.

What goes wrong

The rotary injection pump on the TF Rodeo diesels is gear-driven off the front of the block, and its drive-shaft seal and internal diaphragm sit where a leak drains straight into the timing gear case and then into the sump. When those seals harden with age, diesel runs into the engine oil, so the level on the dipstick climbs on its own and the oil goes thin and watery. Diluted oil loses its film strength and chews out the big-end and main bearings, which is the expensive end of this fault. There was never a recall or a service campaign for it, so the only warning a buyer gets is an oil level that reads above full and oil that smells of fuel.

What you would notice

Oil level on the dipstick keeps rising between services
Engine oil smells strongly of diesel rather than oil
Thin, watery oil on the dipstick instead of thick black oil
Wet diesel or a washed-clean streak around the injection pump
Blue-grey smoke and rough running as the oil thins out

How to check it

Where to look. Front left of the engine - the injection pump sits against the timing gear case behind the crank pulley, and the diesel it leaks ends up in the sump underneath.

Pull the dipstick before the engine is started and look hard at both the level and the smell, because oil that reads above the full mark, looks thin and watery, or smells of diesel is the giveaway.
Wipe it, put it back and pull it again so you are sure of the reading.
Open the oil filler cap and sniff there as well.
Then look down the front of the engine where the injection pump bolts to the block and shine your phone torch on the joint between the pump and the timing case, looking for wet diesel or a clean washed streak in an otherwise grubby engine bay.
Ask the seller how often they top the oil up and whether the level has ever gone up on its own.
Ask to see the last three oil change receipts and check how many kilometres are between them.
If a workshop inspection is possible: have the engine oil sampled for fuel dilution and have a diesel injection specialist pressure-test the pump for a failed drive-shaft seal or diaphragm before you commit.

Parts involved: High-pressure fuel pump.

What it costs to put right

$800 to $2,200 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“Has the injection pump ever been resealed or replaced?”
“Does the oil level ever rise between services?”
“How many kilometres are between the last few oil changes on the receipts?”
“Has the oil ever been changed early because it smelled of diesel?”

Now check the Holden Rodeo you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

IsuzuPup.com forum thread 'fuel in oil'
4BTswaps.com forum thread '4JB1-T injector pump re-seal - DIY possible?'
Clubisuzu.com forum thread '4jb1t fuel pump prob??'
EngineCode.uk Isuzu 4J-series engine guide - injection pump diaphragm failure leaking fuel into the oil

Holden Rodeo buyer questions

Is injection pump drive-end seal leaks diesel into the engine oil (4ja1 / 4jb1 / 4jb1-t) serious on a Holden Rodeo?

We rate it major and common on the Holden Rodeo. The rotary injection pump on the TF Rodeo diesels is gear-driven off the front of the block, and its drive-shaft seal and internal diaphragm sit where a leak drains straight into the timing gear case and then into the sump. When those seals harden with age, diesel runs into the engine oil, so the level on the dipstick climbs on its own and the oil goes thin and watery. Diluted oil loses its film strength and chews out the big-end and main bearings, which is the expensive end of this fault. There was never a recall or a service campaign for it, so the only warning a buyer gets is an oil level that reads above full and oil that smells of fuel.

How much does it cost to fix on a Holden Rodeo?

$800 to $2,200 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Holden Rodeo years are affected?

Our research records this fault on the 1988–2002 Holden Rodeo. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

Pull the dipstick before the engine is started and look hard at both the level and the smell, because oil that reads above the full mark, looks thin and watery, or smells of diesel is the giveaway. Wipe it, put it back and pull it again so you are sure of the reading. Open the oil filler cap and sniff there as well. Then look down the front of the engine where the injection pump bolts to the block and shine your phone torch on the joint between the pump and the timing case, looking for wet diesel or a clean washed streak in an otherwise grubby engine bay. Ask the seller how often they top the oil up and whether the level has ever gone up on its own. Ask to see the last three oil change receipts and check how many kilometres are between them. If a workshop inspection is possible: have the engine oil sampled for fuel dilution and have a diesel injection specialist pressure-test the pump for a failed drive-shaft seal or diaphragm before you commit. Look here: Front left of the engine - the injection pump sits against the timing gear case behind the crank pulley, and the diesel it leaks ends up in the sump underneath.