Last weekend I replaced the mechanical fuel pump on my old 2WD 22r. The very next time I drove it, it began overflowing coolant all over the engine compartment. I don't see how these things could possibly be related, but I thought I would mention it in case there's something about these trucks I don't know.

Coolant is spraying up against the underside of the hood, so I think it's exploding out of the radiator cap. The thermostat housing and water pump look dry, as does most of the area around the head gasket, and I don't see any leaks from any of the hoses (nor have I seen the hoses collapse under load). It's also intermittent; it only seems to happen while I'm on the road. I can't replicate it at any rpm looking under the hood at a standstill.

Coolant is drawn from the overflow when it loses enough through the cap (or wherever else it's spilling out), but coolant is never returned to the overflow.

Here's the kicker: I don't think it's overheating. The temperature gauge appears to be working fine and the engine never gets hotter than it did prior to developing this issue. Just because they are cheap and easy to replace, I installed a new radiator cap and thermostat, but the problem persists.

What could cause so much intermittent pressure in the system that the radiator cap would blow before coolant could dump into the overflow? Any of the things that typically cause excessive pressure in the system-- blockages, collapsed hoses, etc-- usually create that pressure through overheating. Operating temperature and engine performance are seemingly unaffected, however, so I'm confused.

 

Cap failure causing overpressure? er yeah reading faliure, you replaced the cap already. Not likely you got two bad ones but not unheard of either. It's worth taking the time to test them of course.

it sounds odd maybe, but you can always mount a video camera under the hood to get eyes on it under load. It's probably the best way to find out whts going on unless you happen to work at a shop with a dyno. You could take it to the emisssions check place and pretend you didn't know it was going to spray water all over the place, but thats kinda borderline mean and dangerous.

 

Took my first long drive with the new thermostat this morning, and I see that the engine isn't getting as hot as it did with the previous thermostat, like it's opening at a lower temperature and never letting the engine fully warm up.

It also started stuttering under acceleration, something it hasn't done under my ownership. It took twenty minutes on the road for the stuttering to pass.

Something is going on for these problems to hit all at once.

 

Do a compression check, and a test on the coolant for hydrocarbons. If it doesn't find anything you atleast have piece of mind the headgasket appears in good shape.

Test the thermostat (per the FSM) for it's opening temp, also make sure it's not in backwards.

Radiator cap has the correct opening pressure? 13lb.

Coolant system pressure test?

 

No stuttering on my way home from work yesterday. No idea what was causing it.

I got this response from another forum:

 

If you replaced the radiator cap with an OEM it's probably not it. Check the overflow is not plugged up or restricting the flow because of a sharp bend on the overflow tube.

 

Hi Triple---
Hate to say this but you have 7 days before the white smoke pours out the exhaust.

 

No white smoke yet, and it's running strong as ever, but it's still exploding coolant all over the engine compartment during every drive...

 

So... about them radiator caps... OEM or not ?

 

My first course of action was to replace the OEM cap with a cheapo from Autozone. Maybe the original failed and the cheapo did the same, or maybe it's something else entirely.

I'll eventually pick up another OEM and see if that cures the problem. I'm getting used to topping off each morning...

 

Whenever there are cooling issues, the first thing that should be done is a coolant system pressure test. I think they rent the tool at autozone.

Pressurize the system to about 13lb and see if it holds pressure and if there are any external coolant leaks...you will see bubbles. Look everywhere, all hoses, around the head, radiator, themostat etc. If the system is not holding pressure and you see no leaks, then the leak can be internal...which means a bad head gasket. Then you need to do a compression test to see what shape your head gasket is in.

Good luck.

 

If it's coming from the radiator cap area, it might be the solder joint where the fill neck is soldered on. I see those leaking on radiators that come in quite a bit. But then again the top seam and top inlet neck leak on those radiators a lot too. And the top tank is known for getting cracks as well by the fill neck,but that seems to be more common on the v6 radiators. So like what was mentioned above,a good pressure check will help pin point your issue.

 

My local Autozone wants $75/day for the tool and an additional $99/day for the adaptor to fit the little Toyota radiator neck.

 

Three months later and I finally pressure-tested the system. Sure enough, coolant started jetting out of the radiator itself just below the neck.

Anyone have links to sites that sell OEM replacement parts for the 22r? I may as well replace the cheapo Autozone thermostat and radiator cap while I have everything apart.

Where are the drain plugs/bolts in the block of this engine? I'll flush the system while the radiator is out but want to make sure all that nasty garden-hose water is out before I re-fill with coolant.

 

you can get an oem radiator from online toyota part catalogs for about $400 or you can order an aftermarket radiator from rockauto, vista-pro or spectra premium for about $80 and are both quality products, as for an oem cap you'll have to go to the dealer for that.

 

No one mention to burp out the cooling system!

 

Are you sure that's a rent per day situation? The AutoZone here charges for the cost of the tool as if it were new as a deposit, but when you bring it back then give your money back. It ends up costing nothing.

 

Didn't matter, I just went back and asked to use their tools in the parking lot.

 

I'd spring a little extra $ to get the aluminum radiator rather than the plastic. Might want to do a search about the 3-core radiator v. the 2-core version and see if that cooling upgrade would be something to consider too.

 

What's the procedure?

Also, where is the coolant drain plug/bolt in the 22r block?