Can I adjust timing chain on a 1999 ford f150 5.4L without removing engine?

That depends on the motor you actually have 3.0 OHV has a single timing chain it's behind the water pump inside the front engine cover DOHC 3.0 HAS 2 CAMS 1 IN EACH HEAD AND THERE ARE 2 TIMING CHAINS 1 FOR EACH SIDE AND THEY ARE ALSO IN THE SAME PLACE INSIDE THE FRONT COVER THERE ARE NO TIMING BELTS ONLY CHAINS and the DOHC HAS CHAIN GUIDES ON EACH SIDE AND CHAIN TENSION ADJUSTERS YOUR VALVE COVERS SHOULD HAVE TYPE ENGINE ON THEM ALSO LOOK AT YOUR EMISSIONS STICKER ON THE RADIATOR SUPPORT ALSO THERE'S A LETTER DESIGNATION ON YOUR DOOR STICKER THAT YOU HAVE TO LOOK UP ITS ALSO THE 8TH DIGIT ON YOUR REGISTRATION THAT BEING SAID WHAT IS THE PROBLEM THAT YOUR HAVING?

best advice is to get a workshop manual for the engine before you do anything else. It is too costly to work blind.

None of the engines in a Ford Taurus use a Timing Belt. They use a timing chain that should last the life of the engine. There is no service interval for a timing chain.

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I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

The timing it is is not adjustable on these engines. I believe it does not even have a distributor or is distributorless.

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No engine used in the Expedition has a timing belt, they all have timing chains, timing chains never have to be replaced unless they fail or the engine is being rebuilt. On this engine replacing the timing chains for each of the two camshafts (2) cost about $500.00

Yes Ford Explorers are like that, The timing chain tensioners are plastic and need replaced with the chains. The engine has to be removed, please replace all chains and related parts at this time. This will save you money and downtime later. There are multiple chains on these Fords.

no u need to remove the head

not true. SOHC 4.0 tensioner and rails fall apart, allowing the chain to slap and do damage, or even break. book it. in order to replace rioght side cam chain and tensioner, the engine MUST BE REMOVED! if it has balance shaft chain in oil pan, there are a total of four chains in this engine.

The front of the motor has to be removed to access the chains and guides [which may have broken] This can be done without removing the engine, but there are special tools needed to set the chain timing and also for removal of the crank dampner. It is not an easy task.

No engine available in any Ford Explorer uses a timing belt. The cams in all avaiable engines are driven by a chain, this chain has no specific time or mileage recommendation for replacement and in most cases lasts the life of the truck.