Couple questions for first time cooling system rebuild


May 14, 2003
Are you suggesting replacing the PHH the original way is better? Any reason to think the bypass would need to be replaced sooner? If we're talking 10-15 years until the bypass will have to be replaced that sounds alright to me. I like the idea of simplifying the system from two hoses, a metal pipe, and 4 clamps to just one long hose and 2 clamps. But I don't have any personal experience with either way yet.
There's been plenty of debate over the years on whether to bypass. Many have chosen to bypass.

If you are going to have the valve cover off then the lower tube bolt is more accessible.
Aug 1, 2017
Seattle, WA
So based on what I gather from the great comments on this thread, I'm gonna break this job up into two parts. Part 1 is going to be to replace all the cooling hoses I can get to without taking the throttle body out. This will include the PHH, and I think I'll go for the bypass. So I guess I'll be doing that with the valve cover on, but seeing as that's how most do it I can make that work. I'll also do the heater control valve while I'm doing this stuff.

Part 2 will be everything else. I'll take the throttle body out and clean it and the IAC valve. While that's out I'll replace all the vacuum hoses and the smaller radiator hoses that I can't reach with the throttle body in. I'll also do the thermostat and fuel filter, and then I'll take off the valve cover to get the PCV. Knowing me I'm sure to drop some pieces of the old grommet in there so I may as well take it out to do it.

I won't change the valve cover gasket because it seems to be fine. I think I'll be able to get this stuff done in a weekend and I'll end it with a nice coolant flush. Thanks for all the helpful info


May 12, 2015
I have a 1993 Land Cruiser that has been sitting a lot recently due to the fact that I have to keep it at a relative's place. I finally have a little money to throw at some maintenance though so I've decided to rebuild most of my cooling system. Never worked on the cooling system before and I plan to do a detailed write-up with pics to help out anyone else doing this for the first time. Lots of great info out there already but would be nice to have it all in one place.

I just have a couple questions before I buy over $500 worth of parts.

1. Do I need to replace all the hose clamps, or just the ones for the PHH? For the PHH ones, anybody have a link to the clamps? Looks like Wit's End might be out right now

2. I read somewhere that it might be easier to reach some of the hoses with the throttle body out of the car. Is that true? Been thinking about doing a throttle body cleaning, new PCV, and new valve cover gasket anyways so I'll just knock them out all at once if that also helps with the coolant hoses, and the vacuum hoses too while I'm at it. If it doesn't make a difference I might split those into separate jobs.

3. At the moment what I'm planning to get from Wit's End is: radiator hose kit, little hose kit, curved heater hose kit, heater control valve, thermostat kit, pcv kit, vacuum hose kit, and valve cover gasket kit. Is that too much to try and do all in one day? I'm not new to working on my cruiser. I did a knuckle rebuild last year, though it did take a weekend. But I've never worked on the cooling system before so how long should I expect all that to take?

4. Anything else jump out as a must-do "easier while I'm in there" kind of thing?

This might be helpful. Based on my experience, I'm gonna say don't even try to replace the PHH with anything short; go with the 52" bypass...



Mar 11, 2006
might want to have the injectors cleaned too.... I did all this last year. All at the same time. If you can get by without driving it for a week or so just do it all at one time.

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