I know this has been asked and answered a few times but what size vacuum hose fits the 1989 five litre engine thanks in advance.

 

I replaced all of the small diameter vacuum line with 22ft of 4mm thick walled silicone hose from:
http://www.siliconeintakes.com/silic...686d47fdf65361

If you go that route you don't need any boots but you will need a 4-way vacuum tee (or two 3-way tees). Took less than 30 minutes to replace them all, just did them one at a time like plug wires and there was absolutely no thought required.

I went this route so I wouldn't ever have to worry about it again, $0.99/ft is a little more than the local auto parts store vacuum line but their rubber is questionable. I've known people whose new lines rotted out within 2 years, also heard of people not having a single problem for 5 years. Instead of taking the gamble over $0.20/ft I just went with the one and done option. Silicone is designed to handle extreme temperature changes and is more resistant to oil/gas/salt than the standard rubber vacuum hose.

 

Cheers for that info.
With the old girl being 26 years old it's time she had some new vacuum lines thanks for the reply.

 

Is the 4mm size pretty standard size to use? I have a 1994 300 Inline 6 and was wondering, thanks

 

Yes, all of the F150s have the same size vacuum lines. I'm pretty sure that ford used the same size for all of their engines during this time. Including the smaller car engines.