Got a new van, needs work

I couldn't help myself - I bought a another toyota van. It is a 1988 model year with 4wd and a 5 speed. I got it cheap because it has a possible blown head gasket from an overheating event. The van runs and drives but has no power on hills and the compression check (at operating temperature) is 90 psi. The backstory on it is that it ran great until is was run while low on coolant. The previous owner then poured cold water into it while hot (as I understand his story). It never ran right after that. So I suspect a blow head gasket or warped head or both and plan on doing the head work myself. There was no obvious white smoke coming from the tailpipe and the dipstick looks clean. Based on this I do not think there has been any mixing of oil and coolant. Is there anything else that could be damaged from the overheating event? I am looking for other peoples experience with overheating on their vans. The van is an LE model and has a 180K miles on it. Also has a new radiator and a new steering pump. The new radiator was installed after the event. I will be picking the van up this week and may learn more once I start tearing into it. I just wanted to do my homework on what to look for so that I can do it right the first time.

Thanks,

Rusty

Congrats on your purchase and welcome to the site! As you may already know, overheating an engine is one of the worst things that can happen to it. Due to variances in cylinder wall thicknesses and coolant passages, when excessive temps are reached, the expansion of the cylinders is not uniform. Basically a round cylinder becomes slightly oblong or oval. Also, since aluminum expands more than cast iron when heated, the pistons tend to expand slightly larger than the cylinder can accommodate. This creates extreme friction which results in extreme wear on both the pistons and the cylinder walls. Once the engine cools down, there will most likely be scoring on all of your pistons and cylinder walls, and this leaves little passage ways for oil to get up and into the combustion areas. It also messes up compression and that means less power.

Because block is cast iron and the head is aluminum, this means the uneven expansion between these parts can easily over stress the head gasket, causing it to lose it's seal. Warping and cracking of the head is also a common result of excessive overheating.

All that being said, your damage could be minor or major. The only way to tell for sure is a complete tear-down and inspection. I've taken gambles before on things like this with varying degrees of success. Considering the labor involved with the van, doing a head-gasket on an otherwise questionable engine might not be worth the risk. I would pull the head 1st and inspect for obvious damage. If you can see obvious damage to the head and/or gasket but no damage to the cylinder walls it might be worth just crossing your fingers and reworking the top end only. If however you see cylinder wall scoring and/or extreme wear (ridges at the top of cylinder bores), then you will probably want to completely rebuild or look for another good used engine to install. Unfortunately the 4y engine wasn't used much in Japan so the Jap engine exchange places typically won't have them. They used to carry the 3y, but that's only a 2.0 and will slightly suck for power (especially in a 4wd). From what I understand the 3y is now becoming hard to find at the Jap engine places too, so that's probably not much of an option anymore.

You might try posting a request on one of those salvage yard websites and see what happens. There is a seller on eBay selling "good used 4y engines" for $1k each + about $250 shipping. I think he has 6 in stock still. There's also a rebuilder that sells rebuilt long blocks on eBay, but I'd be very wary of them or any other "mass rebuilder" as their quality can be questionable at best. Tim

When driving the van I did not notice any smoke under load. Maybe it is wishful thinking, but I would expect see smoke from combusting oil if the cyl were scored. Do you agree?

Maybe, then again maybe not. Exhaust smoke from engine oil can be hard to see if you are driving (even if you're looking in the mirrors). If you were following behind the van it would be easier to detect (both sight and smell). Another distinction here is how severely it may (or may not have been) overheated. If the guy noticed the temp gauge in the red and immediately shut it off, then it may be okay. If however he ran it until the engine seized, then he probably did some bad damage. People will say anything to sell a vehicle so I tend not to believe most of what they say. More often then not they tend to sugar coat events like that.

Is the compression consistent in all 4 cylinders? If so, even though it seems low it might still be okay. Sometimes the method of testing will effect compression (should be almost double what you say). Still, if they are all about the same I'd start looking at other things. Take a look at the EGR modulator and see if it shows any signs of overheating. If so you may have a plugged up cat converter (would explain the loss of power). Have somebody rev the engine and check the flow of exhaust out the tail pipe too. If the flow seems weak that also indicates a bad cat. If that seems okay and/or the compression is uneven, I would pull the head and hope to see a "smoking gun" with the top end. If you can't find anything with the head or head gasket (that could explain the bad compression) then I'd probably pull the bottom end too and tear it down. What you see at that point will help you decide what to do next. Good luck. Tim

PS: Smoke from engine oil is transparent blue. Smoke from coolant in the exhaust is white (mostly steam and very noticeable). Smoke from too much gas is transparent black and soots up the tail pipe (also burns your eyes and stinks).

I like all of those ideas. Once I get the van I will look into the EGR and the Cat. After running the van up to temperature we took a look under the hatch. I noticed a wisp of smoke coming from the rear of the head. I do not think any conclusions can be drawn from this. I will check the bore diameters of the cylinders when the head is off and look for scoring. The plugs looked good it that counts for anything. The motor never seized during the overheating event according to the owner. I realize that people will say anything to sell a car. However, the van was not posted for sale - I approached him. He had not considered selling the van prior to my inquiry. But I totally understand what you are saying. I just did not get the vibe that he was sugarcoating anything, in fact he was almost embarrassed at having let it overheat.

As a side note, he claims that the van came from California and used to be owned by someone involved in one of these forums. It is a Gunmetal grey (dark grey) LE van without a console refrigerator. It has a sunroof, but not a factory one. The sunroof is more of an aftermarket tilt vent above the passenger and driver seating area. (Just in case someone recognizes it as their old van)

I'll poke it with a stick more when I get it to my house late this week.

Thank you for all the ideas. This is good stuff.

Rusty

Update: My friend Alan (a mechanic) showed me a cool trick to help diagnose a blown head gasket. We started up the van and he removed the coolant (radiator) cap. This was done while the van was still cold. There was bubbling in the coolant and he said they were from exhaust gases pressurizing the cooling system. He told me this is a sign of a blown head gasket. Also, the oil cap had a small amount of emulsified oil (oil and water). Anyway, I will start tearing into it in a day or two.

My last van had noticeable piston slap when cold, but this van does not have that sound. At idle it sounds pretty good.

Rusty